I managed this on paper in 16 minutes, with one Russian poet half-guessed as the more likely arrangement of the anagram letters; the rest was straightforward although required the usual crossword knowledge of CRS and obscure birds and fish to be fully parsed. I especially liked 16a and 26a.
| Across |
| 1 Lookout on Ecstasy tablets needs support to be alert to attack (5,4,4) |
| WATCH ONES BACK - WATCH = lookout, ON E's, BACK = support. |
| 8Stage favourites brought back (4) |
| STEP - PETS, favourites, reversed. |
| 9Established position of one at the top of their game? (10) |
| BRIDGEHEAD - Head person at the game of bridge. |
| 10Standing tires Peg terribly (8) |
| PRESTIGE - (TIRES PEG)*. |
| 11Barnet— specifically the church there (6) |
| THATCH - THAT CH(urch). Barnet fair CRS. |
| 13Stealth tax in Scotland includes obvious vague number (10) |
| COVERTNESS - Insert OVERT (obvious), N into CESS = a Scottish property tax. |
| 16 Good god, a vegetable (4) |
| OKRA - OK = good, RA Egyptian God; a neat clue. I really like okra, if it's fresh, chopped and stir fried in a Bindi Bhaji. |
| 17Language read externally in more than one university (4) |
| URDU - ReaD inside U, U. |
| 18Mount associated with Wellington, a capital (10 |
| COPENHAGEN - Double definition, his horse, and capital of New Zealand. |
| 20 Exercise is to be taken around 55 for strong skeletal structure (6) |
| PELVIS - PE = exercise, IS, insert LV = 55. |
| 22 Finished shed in grey (8) |
| OVERCAST - OVER = finished, CAST = shed. |
| 24Excessively sweet tea popular in Salvation Army church (10) |
| SACCHARINE - SA for the Sally Army, CE = church, insert CHAR, IN. |
| 26Bath water has Virginia withdrawing leg (4) |
| AVON - VA reversed, ON = leg (cricket). |
| 27 People pry only, sadly, to find artificial material (13) |
| POLYPROPYLENE - (PEOPLE PRY ONLY)*. |
| Down |
| 1Flower, perhaps part of extreme dieter’s meal? (11) |
| WATERCOURSE - A water course would certainly help my diet. |
| 2 One involved in petty quarrel over hanging (5) |
| TAPIS - Insert I into SPAT reversed. |
| 3 A way of saying arrogant— but “rich” is another way (9) |
| HUBRISTIC - (BUT RICH IS)*. |
| 4Simplicity one found in part of church, note (7) |
| NAIVETE - I inside NAVE, TE = note. |
| 5See racing boat changing direction (5) |
| SIGHT - EIGHT for racing boat, change the E(ast) to S(outh). |
| 6Russian poet at Oakham, excited about verse (9) |
| AKHMATOVA - Insert V into (AT OAKHAM)*. Anna Akhmatova, 1889 - 1966, born in Odessa so maybe not so Russian. |
| 7Bird with gold colour exterminated in country round Seoul (3) |
| KEA - KOREA has the OR deleted. A kind of large parrot found in New Zealand. |
| 12 Traps tenor in outermost part of building (11) |
| CORNERSTONE - CORNERS = traps, TONE = tenor. |
| 14Ambiguous viola cue disturbed, without question (9) |
| EQUIVOCAL - Insert Q into (VIOLA CUE)*. |
| 15 After bank with genuine style? (9) |
| SINCERELY - SINCE = after, RELY = bank, as in rely on. |
| 19 Professional endorsement, over for a rider (7) |
| PROVISO - PRO, VIS means force or power, hence endorsement? O(ver). I fancied an alternative spelling with a Z, to make VIZ more explainable than VIS, but it doesn't seem to be allowed. |
| 21Rogue’s deception to gain power (5) |
| SCAMP - SCAM = deception, P(ower). |
| 23 Gangster twins reportedly supplying crack all over? (5) |
| CRAZE - Sounds like the Krays, notorious London gangsters. |
| 25Predatory fish, key species (3) |
| ASP - A = key, SP = species. A large European freshwater fish. |