Well, my Internet connection seems fine this morning, so hopefully that means they’ve fixed it properly this time! Anyway, as a few people have already commented, this was an absolute beast of a puzzle. It took me just under an hour, but that was with Bradford’s and Chambers out, and in one case Google (18d). I wasn’t helped by the fact that the instruction about across entries being anagrams of their opposite numbers was missing from my printout version (although it’s there now).
Across
8 C,ASH,MERE - nice straightforward wordplay, good humorous definition. Put me off my guard!
9 TINS,EL - more like Araucaria. “online” = “on line”, line being EL (short for ELevated railway).
10 SKI,N - Calling a ski “footwear” is a bit naughty, but accurate I suppose. To skin is to swindle.
11 SEA C(”Sikh”),APT,A,IN - “I skip” means “I am the skipper”.
14 ASP,(IR),ANT - didn’t like this one - an asp doesn’t sting!
15 WE,AT HER - Guardian = WE is quite common, very tricky definition though. One of the last ones I put in, even though I had guessed by then that it would be an anagram of 17.
17 W(R,EAT)H.E. - another one I wasn’t keen on, because of the r-rust = R-EAT bit. This is a construction that only Araucaria and Azed use, and to me it seems lazy - and, once you’ve seen it a few times, a bit of a giveaway.
20 PAR(rap rev.),TISAN(e)
22 CAST,RO - man of faith because Fidel means faith, I guess. I can’t figure out how RO = “on one side” though.
23 ANAPAESTIC - “cit. sea Pan a” reversed. Two short syllables followed by a long syllable.
25 SI(LEN)T - I wonder if this clue has a typo in it. “Dumb boy in post”. I think it should be “Dumb boy in pose”, because I can’t see how post = sit.
26 MARCH,ESE
Down
1 B(ACK)ACH,E - ack = old letter, being an old signallers’ name for A.
2 W,HEN - as in the phrase “Say when” while pouring someone a drink.
3 CENSU(re),S
5 STRAPPER - “rep parts” reversed. Chambers says “A person who works with straps, esp a groom.”
6 UNI,TAR,1,ANS
13 OUT,STEPPE,D - I put in OVERTOPPED at first, which seriously held me up with 15ac.
16 ENS,HEATH
18 HAR(K)NESS - thanks to Google, I know what an Ena Harkness rose is now. “In harness” means “working”, hence “not yet retired”.
19 A,NATO,MY!
21 AEN(Ena*),EID - Eid being a Muslim festival.
22 CICERO(ne) - Cicero was a Roman orator, but he would have been able to speak Greek as well.
24 SO,HO - I guessed there must be a Greek Street in Soho.