Across:
8 Director general (DG = D-G-) welcomes the German (‘the’ German = der) back (= reverse indicator) (der = -RED-) from Spain (-E) (DREDGE) to do some work on ocean liner? (to do some work on ocean liner/dredge the bottom = DREDGE),
9 Prom is in (prom is in) trouble (= anagram indicator) (prom is in = IMPRISON) with lock-down? (IMPRISON),
10 Some time ago (ONCE) confined in detention centre (confined in ‘detentiON CEntre’ = ONCE),
11 Training sessions for the players (REHEARSALS) at the end of 15 across (end of ‘dress rehearsals’ = REHEARSALS),
12 Cold (C-) caramel (toffee) blows the head (t) (‘toffee’ without ‘t’ = -OFFEE) (COFFEE) as a stimulant one drinks (COFFEE),
14 Atlas in a (atlas in a) compilation (= anagram indicator) (atlas in a = ALSATIAN) produced by Frenchman (ALSATIAN),
15 Mini (DRESS) show trials perhaps (REHEARSALS) (DRESS REHEARSALS) for those gearing up to practice their lines (DRESS REHEARSALS),
18 Awful (= anagram indicator) racism – it (racism it = SCIMITAR) gets waved about a lot and is synonymous with sabre-rattling perhaps (sword = SCIMITAR),
20 Starting primary (starting/first letter of ‘Primary’ = P-) and attempting (trying) to get rid of The Head (t) (‘trying’ without ‘-RYING) (PRYING) – that’s when it becomes more than curious? (PRYING),
22 Instrument (GRAND PIANO) and opening gambit (opening ‘Gambit’ = G-) to get money (monetary unit of South Africa = -RAND) with ATM code (pin = PI-N-) outside area (-A-) office (-O) (GRAND PIANO),
24 It’s about (RE-) to end malpractice (end ‘malpracticE’ = -E-) ahead of failings (a head of ‘Failings’ = -F) (REEF), as it’s a danger to shipping (REEF),
25 Detective (PI = P-I) arrests English (-E-) sales agent (rep) switching (= reverse indicator) (rep = -PER-) old (-O-) for new (-N-) (PEPERONI) seasoned sausage – it’s an alternative (alternative spelling : pepperoni + PEPERONI),
26 In retrospect (= reversal indicator), research site (lab = -BAL-) divides Frenchmen (MM = -M-M) initially eager (initially ‘Eager’ = E-) (EMBALM) to use preservatives in a deadly way (EMBALM).
Down:
1 No port (no port) drunk (= anagram indicator) (no port = PRONTO) quickly (PRONTO).
2 Just sitting around (IDLE) with the French (-LE) papers (ID- papers) open (= position indicator) (IDLE),
3 Clip (clip/cut ‘s’), clip (shear) (‘shear’ without ‘s’ = HEAR), clip, (clip/cut ‘s’), clip (shear) (‘shear’ without ‘s’ = HEAR) (HEAR HEAR)? I totally agree! (HEAR HEAR),
4 Sound of relief (SIGH) as Goliath’s lost a lot? (‘Goliaths’ lost ‘a lot’ = gihs = SIGH),
5 Passes the day, in a manner of speaking (SPEAKS), in States (states = SPEAKS),
6 Most of (k) the record (‘disk’ without ‘k’ = DIS-) will not frustrate (will -SATISFY) (DISSATISFY) or fail to gratify (DISSATISFY),
7 List of names (ROLL) going to Ring (ring = CALL) (ROLL CALL) for the presents? (ROLL CALL),
13 Sole supplier (sole/fish supplier = FISHMONGER) supplying orders of Bass (supplying orders of bass fish = FISHMONGER),
14 Sailor (Able-Bodied seaman = AB-) getting short at the centre (‘sHORt’ at the centre = -HOR) (ABHOR), can’t stand (ABHOR),
16 45 (45 = RECORD-) in hospital (-ER) (RECORDER) but only one in court? (court RECORDER),
17 Agrees with (APPROVES) secretary (PA) to take back (= reverse indicator) (PA = AP-) documents (-PROVES) (APPROVES),
19 Turns up (= reversal indicator), the man upstairs (God = DOG) got to post (-P) good books (Old Testament = OT = TO-) (TOP DOG) by local person whose best in their field (TOP DOG),
21 Ruffle someone’s feathers (NEEDLE) by putting it on the record (NEEDLE on record / to play LP, etc., on turntable/record player),
23 It’s a turning point (AXIS) taking valet off laxatives (taking ‘valet’ off ‘laxatives’ = axis = AXIS),
24 Wedding celebration (40th wedding anniversary = RUBY wedding) in one of the ports (RUBY port).