Across:
8 It’s fashionable (IN-) for Henry (-HAL-) English (-E) (INHALE) to test breathing apparatus (INHALE),
9 Greenish-blue (AQUA-) single (-I-) spirit (-R-UM) (AQUARIUM) secured in tank (AQUARIUM),
10 Remove sloe from Yule logs (remove ‘sloe’ from ‘yule logs’ = yulg = UGLY) – it’s not nice (UGLY),
11 Nuisance on the radio (static = STAT-IC-) admits winner (1st = -IST-) is finally (‘is’ finally = -S) (STATSTSTICS) making sense of the data (STATISTICS),
12 Type of marketeer (FARMER) raising stock issues (FARMER),
14 Cumin is a (cumin is a = MUSICIAN) seedy (= anagram indicator) type found in a pit (MUSICIAN in orchestra pit),
15 Examples (REPRESENTATIVES) of agents (REPRESENTATIVES),
18 Devise (devise = DE-IVES) play (= anagram indicator) about Clare (-CE-) (DECEIVES) fiddles (DECEIVES),
20 Subordinate (JUNIOR) Rising (= reversal indicator) produces an acronym for part of the island (ROI = -IOR) with unionist journalists perhaps (NUJ = JUN-) (JUNIOR),
22 Has an effect on (INFLUENCES) fine uncle’s (fine uncles = INFLUENCES) adaptation (= anagram indicator),
24 Yearn for (PINE for) those from fellowship in England (those from ‘fellowship in England’ = PINE),
25 That woman (-HER-) is taken in by silly (= anagram indicator) tenet (tenet = ET-NET) (ETHERNET) produced by Communications Network (ETHERNET),
26 Party abandons property tax (‘party’ abandons ‘property tax’ = ropetx = EXPORT) for those consumers living aboard (EXPORT).
Down:
1 Show-off (= anagram indicator) in game (in game = ENIGMA) is a mystery to others (ENIGMA),
2 Lost (L-) all the letters (A to Z = -AZ-) – an unknown quantity (-Y) (LAZY) might be good for nothing (LAZY),
3 Judges (MEASURES) get them from The Bar? (MEASURES of drink),
4 Great Dane releases Green (‘great dane’ releases ‘Green’ = atda = DATA) facts and figures (DATA),
5 They’re taught a number of lessons (PUPILS) by slip up (slip up = PUPILS) – and that’s only seen retrospectively? (= reversal indicator),
6 In favour of (PRO-) initial talk (initial ‘talk’ = -T-) to serve (= anagram indicator) notice (notice = -ECTION) (PROTECTION) to security (PROTECTION),
7 Up- (up = PU-) -turn (= reversal indicator) is never ending (‘never’ ending = -R-) and on track (track/pursue = -CHASE) (PURCHASE) for those paying for it (PURCHASE),
13 Ruin (MAR-) to look (-SE-E-) around is not in good shape (-ILL-) by small (-S) (MARSEILLES) French port (MARSEILLES),
14 They’re in the habit (MONKS) of making The Abbey workable (MONKS),
16 There’s no end to this (ETERNITY) entire (entire = ETERNI-) melody (= anagram indicator) by The Yardbirds, for starters (‘the yardbirds’, for starters = -TY) (ETERNITY),
17 Came to terms with (ADJUSTED) what’s dead (dead = AD-ED) wrong (= anagram indicator) about fair (-JUST-) (ADJUSTED),
19 Anne IV (Anne IV = VIENNA) retires (= reversal indicator) to European city (VIENNA),
21 Lift lid off (d) casual drugs (‘downers’ without ‘d’ = OWNERS) for those legally in possession (OWNERS),
23 Describes 19 down (‘Vienna’ = CITY) in Dublin, for instance (CITY),
24 Pinotage grape found on both sides of (‘pinotage grape’ found on both sides = PIPE) channel (PIPE).