Across:
8 Mid-January (mid ‘January’ = -U-) in Milan (Milan) training (= anagram indicator) (Milan = AL-MNI) (ALUMNI) past pupils (ALUMNI),
9 Firm (CO-) at times (-X-) wins a (wins a) complicated (= anagram indicator) (wins a = -SWAIN) (COXSWAIN) job directing a crew overseas (COXSWAIN),
10 Content in newspapers potentially (content in ‘newspapers potentially’ = spot = SPOT) is a blemish on one’s character (SPOT),
11 A line’s a bit (a line’s a bit) out (= anagram indicator) (a line’s a bit = INSATIABLE) in Can’t Get No Satisfaction (INSATIABLE),
12 Upsets (= reversal indicator) elitist (snob = BONS-) to broadcast (air) clip (r) (‘air’ without ‘r’ = -AI) (BONSAI) from one little plant (BONSAI),
14 Basic Sky (basic sky) package (= anagram indicator) (basic sky = SICKBAYS) found in most hospitals? (SICKBAYS),
15 Pledge to keep promise (SWEAR ON THE BIBLE) to half of those in 22 across (half of ‘swear words’ = SWEAR) to broadcast (ON) Gutenberg’s First Book (THE BIBLE) (SWEAR ON THE BIBLE),
18 Endless (t) wine (‘port’ without ‘t’ = POR-) on weekend (‘week’ end = -K-) for college (-C-) dance (-HOP) (PORK CHOP) with the option of a meaty dinner (PORK CHOP),
20 Pool (PUDDLE) party (DUP) backfires (= reversal indicator) (DUP = PUD-) for older party (Democratic Left = -DL-) with ecstasy (-E) (PUDDLE),
22 They cause offence (SWEAR WORDS) opening 6 down (opening ‘swear blind = SWEAR) having a quarrel (having WORDS) (SWEAR WORDS),
24 Give a wide berth to (MISS) what borders on mid-summer madness (what borders on ‘mid-summer madness’ = MISS),
25 The stud’s (the studs = BREEDERS) line managers perhaps? (those managing the line/bloodline are BREEDERS),
26 Writing (from the 3Rs = R-) to greet (greet) criminal (= anagram indicator) (greet = -EGRET) (REGRET) out of guilt (REGRET).
Down:
1 Pop (pop = -PPO) around (= anagram indicator) to open (= position indicator) drink (ALE-) (ALEPPO) from Syrian city (ALEPPO),
2 Melodist sold out (‘Melodist’ ‘sold’ out/without ‘sold’ = meit = EMIT) release (EMIT),
3 Most of (e) the report (‘file’ without ‘e’ = FIL-) to address (IP address = -IP-) one (-I-) negative response (-NO) (FILIPINO) from islander (FILIPINO),
4 Makes a scene (ACTS) with Alliance’s (pacts) missing leader (p) (‘pacts’ without ‘p’ = ACTS),
5 Strikingly unconventional (EXOTIC) engineering (E-) associated with toxic (toxic) mixture (= anagram indicator) (toxic = -XOTIC) (EXOTIC),
6 Promise (SWEAR BLIND) of endless (end ‘less’ = S-) sport (sport/have on = -WEAR) on screen (BLIND) (SWEAR BLIND),
7 Detective’s (DI’s = DIS-) unlikely to inform criminals, for instance (-LOYAL) (DISLOYAL), or dissident (DISLOYAL),
13 Perhaps not a patch on (STARK NAKED), say (= homophone indicator), steak (‘steak’ = ‘stake’ = STA-KE-) stuffing mix (= anagram indicator)? Rank (rank = -RK NA-) alongside tail end of chateaubriand! (tail end of ‘chateaubriand’ = -D) (STARK NAKED),
14 Part of the exercise (SIT-UP) is to pay attention (SIT UP and pay attention),
16 Floors boring type (floor’s boring type = WOODWORM) and calls (= homophone indicator) cops (‘cops’ = ‘copse’ = WOOD-) after opening (= positional indicator) computer virus (-WORM) (WOODWORM),
17 Publicity (EXPOSURE) for show (EXPO-) guaranteed (-SURE) (EXPOSURE),
19 A man synonymous with the birds (falconer / HAWKER) from Merchants Market (HAWKER),
21 Pay attention to (LISTEN) Leninist dropping in (‘Leninist’ dropping ‘in’ = lenist = LISTEN),
23 Relax (REST) – it’s embraced by the Welfare State (it’s embraced by the “Welfare State” = REST),
24 Local fools (MUGS) in Home Guards missing? Oh dear! (‘Home Guards’ missing ‘Oh dear’ = mgus = MUGS).