A nice variety of clues from Neo today
The NE quadrant held me up for a while, and both TETRODE and MARTINGALE were unfamiliar to me.

| ACROSS | ||
| 1 | CHARMER |
One seducing US singer reserves a room (7)
|
| CHER (US singer) around (reserves) {A + RM (room)} | ||
| 5 | TOEHOLD |
First established position to see bishop exiting (7)
|
| TO [B]EHOLD (to see) minus (exiting) B (bishop) | ||
| 9 | ETHER |
Subtract any number from lower number (5)
|
| [N]ETHER (lower) minus (subtract . . . from) N (any number) | ||
| 10 | EMPTINESS |
Vacancy M&S filled with essentially dippy case? (9)
|
| {EM (m) + ESS (s)} around (filled with) {middle letter of (essentially) [DI]P[PY] + TIN (case)} | ||
| 11 | VAMPIRE BAT |
Claret consumer in club following Siren and Fury (7,3)
|
| VAMP (siren) + IRE (fury) + BAT (club) | ||
| 12/6 | FIRE EXIT |
Burning issue (4,4)
|
| Cryptic definition | ||
| 14 | AGE OF CONSENT |
This attained so one can get involved with female (3,2,7)
|
| &lit and anagram of (involved) {SO ONE CAN GET + F (female)} | ||
| 18 | FAMILY CIRCLE |
Blood group O? (6,6)
|
| Cryptic definition/&lit and FAMILY (blood group) + O (circle) | ||
| 21 | LARK |
Mad King Lear loses throne at last in play (4)
|
| Anagram of (mad) {K (king) + L[E]AR minus (loses) last letter of (at last) [THRON]E} | ||
| 22 | BLANK VERSE |
Poetry not written on very old language (5,5)
|
| BLANK (not written on) + V (very) + ERSE (old language) | ||
| 25 | EASY CHAIR |
Relax in this undemanding academic post (4,5)
|
| EASY (undemanding) + CHAIR (academic post) | ||
| 26 | NANCY |
Article recalled clubs in New York City (5)
|
| AN (article) reversed (recalled) + {C (clubs) inside (in) NY (New York)} | ||
| 27 | TETRODE |
Walked into Peg in the Tube (7)
|
| TROD (walked) inside (into) TEE (peg), with capitalization misdirections | ||
| 28 | EXAMPLE |
School test regularly applied pattern (7)
|
| EXAM (school test) + alternate letters of (regularly) [A]P[P]L[I]E[D] | ||
| DOWN | ||
| 1 | CLEAVE |
Cell initially needing permission to divide (6)
|
| First letter of (initially) C[ELL] + LEAVE (permission) | ||
| 2 | AT HOME |
In moat he struggles (2,4)
|
| Anagram of (struggles) MOAT HE | ||
| 3 | MARTINGALE |
Swallow good beer going for broke at casino (10)
|
| MARTIN (swallow, i.e., the bird) + G (good) + ALE (beer) | ||
| 4 | REEVE |
Old magistrate once a Kent player? (5)
|
| Double definition, the second referring to Christopher Reeve, who played Clark Kent aka Superman | ||
| 5 | TAP DANCER |
Rapper on stage to milk a reindeer? (3,6)
|
| TAP (to milk) + DANCER ([one of Santa’s] reindeer), apparently referring to the percussive sound of the shoes | ||
| 7 | ONE-SIDED |
Partial description of Möbius strip (3-5)
|
| Double definition | ||
| 8 | DESSERTS |
Cobblers perhaps tense up (8)
|
| STRESSED (tense) inverted (up) | ||
| 13 | UNCLE VANYA |
Crazy lunacy having Welshman in Chekhov drama (5,5)
|
| Anagram of (crazy) LUNACY around (having) EVAN (Welshman) | ||
| 15 | OSCILLATE |
Liverpudlian singer in old set rewritten for swing? (9)
|
| CILLA [Black] (Liverpudlian singer) inside (in) {O (old) + anagram of (rewritten) SET} | ||
| 16 | AFFLUENT |
Waste initially cleared after a flush (8)
|
| A + [E]FFLUENT (waste) minus first letter (initially cleared) | ||
| 17 | SMART SET |
Sophisticated group examine sheep from below (5,3)
|
| {TEST (examine) + RAMS (sheep)} all inverted (from below) | ||
| 19 | PRE-NUP |
Rules of engagement? (3-3)
|
| Cryptic definition | ||
| 20 | RETYPE |
Key again right with Jaguar model (6)
|
| R (right) + E-TYPE (Jaguar model) | ||
| 23 | NURSE |
Tend to course around Seine’s banks (5)
|
| RUN (course) inverted (around) + outside letters of (banks [of]) S[EIN]E | ||
| 24 | ECHO |
Parrot in Square Mile on horse with duck (4)
|
| EC (Square Mile, i.e., the City of London) + H (horse) + O (duck) | ||