Across:
1 Speak highly of (ADMIRE) Bill (AD-) Marsh (-MIRE) (ADMIRE),
4 People from Spain and Portugal (IBERIANS) and Serbia in (Serbia in) trouble (= anagram indicator) (Serbia in = IBERIANS),
9 Edit (REDUCE) crude (crude = REDUC-) novel (= anagram indicator) giving it direction (east = -E) (REDUCE),
10 Turn your back (ABDICATE) on sailor (able-bodied seaman = AB-) taking lady friend (-D ATE-) around island (-I-) on top of craft (top of ‘Craft’ = C) (ABDICATE),
12 Dramatise (OVERSTATE) what’s on top of (OVER-) small (-S-) foreign museum (-TATE museum) (OVERSTATE),
13 Jump for joy (EXULT) or limp out of Multiplex? (‘limp’ out of ‘multiplex’ = ultex = EXULT),
14 One of the generals in the sick sense (one of the general practitioners = PRACTITIONER) requires surgery to work? (PRACTITIONER),
18 Gives the right to drive (TRAFFIC LIGHT) trade (TRAFFIC) that’s insignificant (slight) starting off (s) (‘slight’ without ‘s’ = LIGHT) (TRAFFIC LIGHT),
21 Creator (CAUSE) of Genesis? (CAUSE),
22 What isn’t plain, in the material sense (PATTERNED), is a set of instructions (sewing/knitting PATTERN-) for writer (-ED) (PATTERNED),
24 Gave a name to (ENTITLED) crazy (= anagram indicator) Lent diet (lent diet = ENTITLED),
25 Anoint (anoint) sick (= anagram indicator) (anoint = NATION) of the republic, for instance (NATION),
26 Military operation opens (‘Military Operation’ opens = MO-) with chaos (anarchy) decapitating (a) (‘anarchy’ without ‘a’ = -NARCHY) (MONARCHY) those in kingdom (MONARCHY),
27 Problems (MESSES) with local pickle (‘local’ pickle = mess) stew? (‘local’ stew = mess) (mess x 2 = MESSES).
Down:
1 Spread (AIR) new (= anagram indicator) crops (crops = CORPS) (AIR CORPS) for one of those in the services industry (AIR CORPS),
2 Half of what’s wrong (half of what’s ‘EVil’ = -EV-) in The Press (media = MEDI-A-) is primarily like (primarily ‘Like’ = -L) (MEDIEVAL) something out of the dark ages! (MEDIEVAL),
3 Plays music (ROCKS) produced by more than one of The Stones (ROCKS),
5 Acrimony (bile = BI-LE) over a follower (‘a’ follower = -B-) from club (SOCIETY) (BIBLE SOCIETY) distributing good books (BIBLE SOCIETY),
6 Bring those downstairs upstairs presumably (RAISE HELL) to cause a commotion (RAISE HELL),
7 Has an influence on the count (ABACUS), as what’s monitored is not in sodium carbonate (‘monitored’ is not in ‘sodium carbonate’ = sucaba = ABACUS),
8 Money (-CENT-) in ship (SS = S-S) (SCENTS) picked up by the boxers, for instance (picked up by the dogs = SCENTS),
11 What the best man uses to slag off the groom (PART OF SPEECH), in a manner of speaking (PART OF SPEECH),
15 Bully (TORMENTOR) for the people (-MEN-) behind (= positional indicator) The Hill (TOR-) forming the basis for a lawsuit (tort) briefly? (t) (‘tort’ without ‘t’ = -TOR) (TORMENTOR),
16 Siege can (siege can) damage (= anagram indicator) (siege can = AGENCIES) the levers of American government (AGENCIES),
17 Female nags mate (female nag’s mate/mare’s mate = STUD- horse) sent (sent) off (= anagram indicator) (sent = -ENTS) (STUDENTS) with those who are still learning (STUDENTS),
19 Squeal (squeal/howl = SCREAM) to serviceman cutting vine (‘serviceman’ cutting ‘vine’ = sercma = SCREAM),
20 Control on the radio (BUTTON) for a shirty type (BUTTON),
23 Put a line through (ERASE) some disclaimer as expected (some ‘disclaimER AS Expected’ = ERASE).