Not much to comment about in this one. A couple of relatively obscure words but not too difficult to determine from the wordplay. Some enjoyable clues, I particularly liked 3D.
Across
1 IFFIER IF FI (mid-wIFe forwards and backwards) ER (expressed hesitation)
4 CARBOLIC COLIC (complaint) about *(BAR)
10 SYBARITIC *(CITY BAR IS)
11 WORKS dd
12 ARIA *(AIR) A
13 ALL THE RAGE A G (first letter of genius) inside ALL THERE (of normal intelligence) – the definition was ‘in’
15 CRUMBLE C (first letter of confectioner) RUMBLE (discover the truth about)
16 CROWDS CROWS (birds) about D (500)
19 AENEAS second letters of ‘tAvErN bEcAuSe’ – in Greco-Roman mythology Aeneas ‘travelled’ from Troy to Italy and founded Rome
21 DREAM UP *(PRAM DUE)
23 CONFERENCE dd
25 ACOL A CO (company) L (letterhead ie first letter of letter) – Acol is a method of bidding in the card game bridge
27 EPSOM P (parking) in *(SOME)
28 LATERALLY LATER (succeeding) ALLY (partner)
29 SAYONARA SAY (for example) *(AARON)
30 WOODEN O (love) in WODEN (God)
Down
1 INSTANCE IN (batting, a cricket term) STANCE (position)
2 FEBRIFUGE FEB (month) *(FIGURE) – febrifuge is apparently a medicine that reduces fever
3 EARS cd – ears are ‘auditors’ and ‘Anthony’s loan request’ is that famous line “Friends, Romans and countrymen, lend me your ears …..”
5 ASCETIC AS (like) CETIC (Celtic, a Scottish football team, minus ‘l’ the back of fall)
6 BOWLED OVER DOVE (bird) in BOWLER (hat)
7 LORNA hidden word in ‘isabeL OR NAtalie’
8 COSSET COS (lettuce) SET (place)
9 ATTLEE TT (empty tent) in A LEE (shelter)
14 ABLE SEAMEN *(A MALE’S BEEN)
17 DOMICILED *(OLD MEDICI)
18 APOLLYON A POLLY (parrot) ON (aboard) – Apollyon was a Biblical destroyer or devil
20 STELLAR STELLA (woman’s name) R (right)
21 DUCATS DU (dumb with MB for ‘physician’ removed) CATS (animals)
22 SCREWS dd
24 NASTY ST (street) in *(ANY)
26 BRIO BRI (middle letters of Cambridge) O (first letter of October)