Across:
8 Not following the rules (UNFAIR) in organisation (UN-)? Report (= homophone indicator) those in 2 down! ('fare' = 'fair' = -FAIR) (UNFAIR),
9 By (B-Y) taking in Trim (cut) priest (‘Rev’ without ‘v’ = -RE-) and heartless (c) vicar (heartless ‘viCar’ = -VIAR-) (BREVIARY), father said it all (BREVIARY),
10 I’ll give you that (CEDE) sample of Crème de Cacao (sample of ‘crèmE DE Cacao’ = edec) to knock back (= reverse indicator) (edec = CEDE)
11 Frenchman (M-) is (-IS-) linked to criminal (-CON-) outlet (-DUCT) (MISCONDUCT) synonymous with unethical behaviour (MISCONDUCT),
12 Work with (ASSIST) foolish figure (ASS-) to get very good marks at university (1st = -IST) (ASSIST),
14 Caught (C-) Michael (Michael) mixing (= anagram indicator) (Michael = -HEMICAL) (CHEMICAL) drug (CHEMICAL),
15 A toxic campaign that affects the atmosphere (CHEMICAL WARFARE) for most of those in 24 across (most of ‘wars’ = WAR-) following (= positional indicator) 14 across (‘chemical’ = CHEMICAL) and 2 down (‘fare’ = -FARE) (CHEMICAL WARFARE),
18 Starters of salads, omelettes (starters of ‘Salads Omelettes’ = SO-), cheese (-BRIE-) and sides to take away (sides to ‘Take awaY’ = -TY) (SOBRIETY)? Presumably, it’s not for those who are tight! (SOBRIETY),
20 Reviews (= reversal indicator) school (-S) visit (call = L-LAC-) around institute (-I-) (LILACS) by Olive’s relatives (LILACS related to the olive family)
22 Carol (sing = S-ING) consumes hotchpotch (-WELTER-) (SWELTERING) of local baking (SWELTERING),
24 Water sports dismissing protest (‘water sports’ dismissing ‘protest’ = wars = WARS) as struggles with a number of general employers (general employers = army / WARS),
25 Isn’t (isn’t) wrong (= anagram indicator) (isn’t = INS-T) about unfinished (k) lorry (truck) (‘truck’ = -TRUC-) (INSTRUCT) or coach (INSTRUCT),
26 It’s arbitrary (RANDOM) in capital (monetary unit of South Africa = RAND-) of Morocco, for starters (‘Of Morocco’ for starters = -OM) (RANDOM).
Down:
1 Save (UNLESS) a French ('a' French = UN-) takeaway (-LESS) (UNLESS),
2 The going rate for The Tourists (FARE) or Blondie (fair) on the radio (= homophone indicator) locally (‘fair’ = FARE),
3 Runner (-MAT-) in Cairo (Cairo) confused (= anagram indicator) (Cairo = ARO-IC) (AROMATIC) like Rosemary, for one (rosemary herb is AROMATIC),
4 Odd Brits (odd letters of ‘BrItS’ = -BIS) following (= position indicator) current (I-) (IBIS) seen by birdwatchers (IBIS),
5 Far away (REMOTE) from exploding (= anagram indicator) meteor (meteor = REMOTE),
6 Did a sinful (did a sinful) action (= anagram indicator) (did a sinful = DISDAINFUL) on one’s high horse locally (‘on one’s high horse’ locally = DISDAINFUL / showing contempt),
7 A (A-) judge from the past (Resident Magistrate = -RM-) takes over the meeting (the chair = -CHAIR) (ARMCHAIR) – it’s handy when one is sitting (ARMCHAIR),
13 Wickedness (IMMORALITY) of losing heart (t) in eternal life (immortality) (‘immorTtality’ without ‘t’ = IMMORALITY),
14 The black stuff (coal-) say (= homophone indicator) (‘coal’ = ‘cole’ = COLE-) to go with the last of oily (last of ‘oilY’ = -Y) (COLEY) fish (COLEY),
16 Double-cross (HOODWINK) local criminal (HOOD-) on a flutter (-WINK) (HOODWINK),
17 Really go (really go) crazy (= anagram indicator) (really go = ALLEGORY) producing a fable (ALLEGORY),
19 Everything the viewer is aware of (EYEFUL) is a joy to behold (EYEFUL),
21 Incentive (CARROT) concealed by conductor? Rachmaninoff’s (concealed by ‘menTOR RAChmaninoff’ = torrac) backing! (= reverse indicator) (torrac = CARROT),
23 Tiny amount (IOTA) of cases dropped by associate (‘cases’ dropped by ‘associate’ = aoit = IOTA),
24 Women (W-) in (-IN-) Government (-G) (WING) faction (WING).