Pleasing puzzle from this imaginative setter which I found on the easy side, but made one mistake - thank’s for explaining it below, Geoff.

* = anagram

1 SMELLING SALTS Tip-top double definition

10 LOONY Two phrases meaning this    (No - it’s LOOPY which is very good)

11 AR (AU) C ARIA A Guardian setter who needs little introduction is named (pseudonym) after this (monkey puzzle) tree.

12 BELL IN I

13 SETTING Excellent double definition, raising a smile

14 LEG ATE

15 DI (SPROg) VE

18 ALTERING (triangle)*

19 BAD EGG Double defintion

21 MOO RAGE More good fun

22 O C (TAG) ON

24 N EAR THING North Pole earthing

25 C RATE An old decrepit car - very good clue c = speed of light

26 HAPPY FAMILIES (if he plays pa I’m)*

DOWN

2 MOONLIGHT S ON A TA

3 L (AY S) ISTER (say)*

4 IRA (QI) S s (IQ) ari all reversed

5 GOATSKIN (asking to)*

6 A SCOT

7 TURN IN ONES GRAVE (Run into nerve gas)*

8 G(L)OB AL (W)ARMING w = world’s heading (first letter) gob = trap = mouth. I suspected this straightaway from the definition and enumeration. As it was in the leftmost column and intersected six across entries giving first letter, it made the rest of the puzzle much easier for me.

9 HANG S ENG IN(D)E X Another one I guessed from enumeration and definition before working it all out.

16 P (R) ACT I CAL (California)

17 UN BE (L I) EF

22 DO D GEM Dodgems at the fun fair, hence, ‘fair thing’

22 AC T UP

It’s a fair cop!  Theme of  ’places of confinement’  today, but a light-hearted puzzle in spite of its subject.

ACROSS

1.     PRISON - ( p-<no sir - the theme of the puzzle and an easy starter.)
4.     CHOKEY - ( choP-key.  Dated slang for a house of correction)
8.     QUARREL - ( qua-r-rel.  Qua - in the capacity of-  Latin derivation)
9.     UPGRADE - ( * dear pug)
11.   ADVENTURER - (*dave return)
12.   IDLE - ( I’d-le)
13.   CLINK - ( c-link - another slang word for ‘prison’)
14.   ARMCHAIR  - ( a-rm-ch–air - R. Marine is known as a ‘jolly’)
16.   ORIGANUM - ( <a giro - num.  A popular cooking herb)
18.   GULAG - ( gag around u-l. A Gulag was a soviet penal labour camp.)
20.    HYMN - ( alternate letters of The Yemen)
21.   CONFISCATE - ( * accent is of)
23.   FOREARM - ( * a former - to  forewarn is to forearm-  not to be confused with the bit
                                         between elbow and wrist.)
24.   MINNOWS - ( min-now’s - little fish, usually found in brooks and pools)
25.   BAGNIO - ( * boaTing - take out the heart. An archaic prison for slaves,
                                  especially in the Orient.)
26.   COOLER - ( cryptic definition for the cooling drink - also slang for ‘prison’)

DOWN

1.     POUND - ( po-u-nd .  U is a Burmese Honorific, similar to Mr.  Famously, U Thant
                                Secretary General of the United Nations. Pound is a place of
                                confinement or punishment.)     
2.     ISRAELI  - ( i-*serial)
3.     OVERTAKEN - ( overt-a ken-O. Keno is a game of chance, adapted from Lotto
                                       for gambling. I feel this is a slightly strained definition, as’ went from’
                                       surely needs ‘ WAS overtaken’?)              
5.     HOPER - (ho-per)
6.     KURDISH - ( homophone of curd-is-h.  The white flowers of the cauliflower are known as
                               curds, possibly because of the their creamy foaming appearance.)
7.     YODELLING - (*lonely dig)
10.   TREATMENT  - ( treat-men-t. A treat can sometimes be a present.)
13.   CURRYCOMB - ( cryptic description. - an implement for grooming a horse)
15.   MAGNIFICO - ( * I’m facing - a Venetian nobleman, or a person of rank and
                                      importance.)
17.   GINSENG  -( gins-eng.  - various plants are sold under this  name, to promote health)
19.   LACUNAL -( hidden in CADIL lac un-al Lowed.  Having empty spaces or cavities,
                                especially in bones, snakeskins etc.)
21.   CORGI - (c-or-gi.  It’s that dog again!)
22.   TOWER - ( double or cryptic definition - a tower {cf the Prince in the–}  or
                             a vessel which tows, e.g. the tug.

Note that in (another) relaunch, the crossword has moved back towards the end of the main paper p. 101 of 104 in my edition. Solving time, 17 mins.

* = anagram < = reversed

ACROSS

1 SANDBAGGER Double definition

6 NUMB (er) One is a number

9 HAN (DOVER) S

1O B (ASS) O (OB = old boy)<

11 BERKELEY CASTLE (Celeb takes lyre)*

12 SP (RA) IN

14 RAFFLES Double definition

16 A (UNTIE) S

18 DERIDE hidden

19 A FLEA IN ONE’S EAR Double definition

22 ADI (O) S (said)*

23 E M BRA SURE

24 A (ST) I A1 = excellent

25 BOTTLENECK Double definition

DOWN

1 SO HO (OS)<

2 NO N CE

3 BLOCK CAPITALS In which the clue is written

4 G REMLIN (Merlin)*

5 E S SAY ER

7 UNSETTLED Double definition

8 BLOKEISH (Hol bikes)*

10 BEAUFORT SCALE Excellent cryptic definition

13 PA (NELL I) ST

15 LAVA-LAVA lava (hot stuff) twice. A Polynesian skirt. Amusing surface

17 SAN REMO (Moaners)*

18 DINGBAT (debating)* less e = energy

20 A CUTE

21 WEEK Referring to Old Testament account. Another very good surface.

Mudd gave us a few sterling clues in this puzzle (2D, 18D, 26D), one that I think is weak (19D).

Across
1. WOMBAT - TAB (bill) + MOW (cut) all backwards
4. BLACKOUT - LACK (shortage) in BOUT (attack)
9. NINETY - Y (unknown) + TEN (figure) + IN (in) all reversed. I did not figure out this wordplay originally — see comments below.
10. MONORAIL - ON (on) + OR (gold) in MAIL (post)
12. SPECTRUM - anagram of CRUMPETS
13. ACCENT - homophone (”axe sent”)
15. ROOK - double definition
16. GASTRONOMY - G (good) + ASTRONOMY (looking up)
19. COAT OF ARMS - anagram of FOR A MASCOT
20. PEEP - double definition
23. PASTEL - PAST (after) + EL[even] (eleven, flat out)
25. SCREW TOP - CREW (men) in STOP (bar)
27. TROTTING - T (time) + ROTTING (going off)
28. ACTUAL - AC (account) + U (university) in TAL[e] (short story)
29. LUCKY DIP - [p]LUCKY (courageous going topless) + DIP (swim)
30. PEPPER - ???. This strikes me as a non-cryptic clue. Am I missing something? (See comments below.)

Down
1. WINDSOR - WINDS (snakes) + RO[of] backwards
2. MINNESOTA - anagram of NOMINATES
3. ASTUTE - STU[pid] (semi-foolish) in ATE (goddess)
5. LOOM - double definition
6. CHOW CHOW - double definition
7. OSAGE - O (old) + SAGE (wise)
8. TOLSTOY - anagram of LOST + TOY (play)
11. RUNAWAY - A (article) in RUNWAY (path of aircraft)
14. STOMACH - double definition
17. OVERTRUMP - OVERT (frank) + RUMP (behind)
18. COVENTRY - COVEN (women practising spelling) + TRY (test)
19. CAPITAL - double definition
21. POPULAR - U (yew we hear) in POPLAR (tree)
22. RESCUE - anagram of secure
24. STOIC - I (one) in COTS (beds) reversed
26. ANTI - [m]ANTI[s] (prayer without limits)