Across:
8 Pilot (DRIVE-) left (-L) (DRIVEL) Twitter (twitter/gabble = DRIVEL),
9 In the end (= position indicator), rascal (rogue) loses head (r) (‘rogue’ without ‘r’ = -OGUE) and face (DIAL-) (DIALOGUE) in talks (DIALOGUE),
10 Yank (PULL) in drag? (PULL),
11 Huge regret (huge regret = TREE-HUGGER) disturbing (= anagram indicator) one of The Greens embracing the elders (TREE-HUGGER),
12 Tips (ADVICE) for Bill (AD-) with bad habit (-VICE) (ADVICE),
14 Resist the temptation (RESTRAIN) to show off (= anagram indicator) trainers (trainers = RESTRAIN),
15 Where Caesar crossed the Rubicon (POINT OF NO RETURN) with ace? (in tennis, ace is not returned / POINT OF NO RETURN),
18 Not ignorant (LITERATE) of elite art (elite art = LITERATE) movement (= anagram indicator),
20 Sharp tone (ABRUPT) is key (music key A-) to initial potential (initial ‘potential’ = -P-) in dry wine (dry wine = -BRUT) (ABRUPT),
22 Cadetships (‘cadetships’ = DISPATCHES) all at sea (= anagram indicator) in ships (ships/sends off = DISPATCHES),
24 Writing (from the 3Rs = -R-) in decline (dip = D-IP) (DRIP) – or that’s the leak? (DRIP),
25 Pub (BAR-) set up by sommelier in The Cellar (-RACKS) (BARRACKS) in private quarters (private/army quarters = BARRACKS),
26 Report (RELATE) from central Florence (central ‘Florence’ = RE-) on The Dead (the dead = -LATE) (RELATE).
Down:
1 Guinness head (‘Guinness’ head = G-) on a number of beers from the bar (-ROUND) (GROUND) – the earthy type (GROUND),
2 Track circuit (OVAL track racing) of dirge from Gore Vidal (‘dirge’ from ‘Gore Vidal’ = oval = OVAL),
3 It’s very fashionable (ALL THE GO) for lethal (lethal = ALL THE) plan (= anagram indicator) to get green light (green light = GO) (ALL THE GO),
4 Just sitting around (IDLE) – it’s the upsetting (= reversal indicator) part of unwieldiness (part of ‘unwieldiness’ = (eldi = IDLE),
5 Hideaways (CACHES) by a (-A-) church (-CH-) in Clare (C-E-) beside school (-S) (CACHES),
6 Dance partner (SONG- and dance) is a bookmaker (-WRITER) (SONGWRITER) who does his work in bars perhaps? (SONGWRITER writes in bars/beats),
7 Is it better (SUPERIOR) to rise up or (rise up or = SUPERIOR) run? (= anagram indicator),
13 Set up (= reversal indicator) to take a quick glance (peek = -KEEP-) inside secret (inner = INN-ER-) story initially (‘story’ initially = -S) (INNKEEPERS) of those behind bars (INNKEEPERS),
14 Class (RANGE) of Orangeman ignoring moan (‘orangeman’ ignoring ‘moan’ = rgean = RANGE),
16 Old (O-) European capital (Riga, capital of Latvia = -RIG-A) overlooking popular (-IN-) lake (-L) (ORIGINAL) that’s untouched (ORIGINAL),
17 Calm (calm/comfort = REASSURE) users are (users are = REASSURE) all at sea (= anagram indicator),
19 Auntie (‘auntie’ = ‘anti’ = ANTI-) broadcasted (= homophone indicator) college (-C-) and school (-S) (ANTICS) pranks (ANTICS),
21 Making contact with distributor (POINTS / contacts in the distributor) for new (= anagram indicator) piston (piston = POINTS),
23 Put on (HOST) old (-O-) substitute initially (‘substitute’ initially = -S-) during interval (half-time = H-T) (HOST),
24 Matt (DULL) sides with Duke of Argyll (sides with ‘Duke of Argyll’ = DULL).