A generally straightforward puzzle today with accurate cluing in most instances though 11a was a little misleading in that ‘grain’ needed to provide ‘crop’ and ‘store’ ‘silo’ whereas a silo is a grain store.
Across
1 PROVERB ROVER (dog) in PB (lead)
5 THEOREM ORE (mineral deposit) in THEM (the others)
9 COPED P (quietly) in CO-ED (both sexes)
10 TRUNCHEON RUN (speed) CHE (revolutionary) in TON (100)
11 ACROPOLIS A CROP (grain) SILO (store) reversed
12 EXERT EX[p]ERT (pundit with no pressure)
13 DOUGH DO (the same, ditto) UGH (repugnant sound)
15 FORTUNATE TUNA (fish) in FORTE (strength)
18 STEAMED UP d&cd
19 RABID *(A BIRD)
21 ASDIC A CID’S (detective group’s) reversed
23 BILATERAL *(BARE IT ALL)
25 DECADENCE DECADE (years) [o]NCE
26 WRING homophone of ‘ring’ (telephone when talking)
27 MORELLO MORE (extra) L (large) LO (look)
28 TORRENT R (river) in TO RENT (for hire)
Down
1 POCHARD CHAR (fish) in POD (whale group)
2 OPPORTUNE OP (work) TUN (barrel) in PORE (small opening)
3 END UP [s]END UP (start off parody)
4 BOTTLE-FED *(TO BE LEFT) D (day)
5 TRUSS dd
6 EXCHEQUER EX (former) homophone of ‘checker’ (investigator)
7 REEVE E (drug) in EVER (always) reversed
8 MANATEE ATE (goddess) in MANE (hair)
14 HOMICIDAL *(ACID) in HOMIL[y] (endless sermon)
16 REPELLENT ELL (old measure) in REPENT (show contrition)
17 AUBERGINE *(ARE BEGUN I)
18 STARDOM A in ST RD (two ways) OM (gong)
20 DELIGHT DE (of, in French) LIGHT (land)
22 DECOR DEC (month) OR (gold)
23 BINGO hidden in ‘cuB IN GOod’
24 TOWER *(WROTE)