I give my COD nod to 12 across, since it is such a fine word, by no means onomatopoeic but conjuring up nonetheless the sense of the thing it denotes by its sound and by its form. Just under 16 minutes for me.
ACROSS
1 Hole-dweller nipped by male ferret (6)
HOBBIT – HOB (male ferret) BIT (nipped)
4 Fork out immense amounts for explosive warheads (8)
PAYLOADS – PAY (fork out) LOADS (immense amounts); an admirable clue, since the weapons industry spares no effort in delivering solutions that will burn holes in the deepest pockets
10 Gear Oscar hired out to a court jester (9)
RIGOLETTO – RIG (gear) O (Oscar) LET TO (hired out to) for the chap in the opera whose main claim to fame is the aria La donna e mobile (‘My wife has her own car now’)
11 Head of Leeds University entertained by eccentric Scotsman (5)
CALUM – LU in CAM (an eccentric or cam is ‘a slider or roller attached to a rotating shaft to give a particular type of reciprocating motion to a part in contact with its profile’; tsk! as if we didn’t know that)
12 Very small amount of tin trapping biting insect (7)
SMIDGEN – MIDGE in SN (symbol for tin)
13 Go back in time ultimately with idea for poem (7)
ECLOGUE – GO reversed in [tim]E (time ultimately CLUE (idea)
14 Model banker at table’s description of what he does? (5)
IDEAL – this is not the chap who give himself enormous bonuses but the fellow who works say in a casino and deals cards
15 Strong dislike of retired minister visiting a Swiss town (8)
AVERSION – REV reversed in A SION (Swiss town)
18 Work in city randomly accepting notes to emend (4-4)
COPY-EDIT – OP (work) in anagram* (‘randomly’) of CITY in which a couple of musical notes, to wit, E and D, are placed
20 Young greyhound, perhaps — one kept by king and queen (5)
RACER -ACE in R (rex) and R (regina)
23 Provoke current lover (7)
INFLAME – IN FLAME
25 Greek character, very small, working outside (7)
OMICRON – MICRO in ON (working)
26 Developed form of life — the writer’s, in the past (5)
IMAGO – I’M AGO
27 Feature of marsh plant, one ruminants rejected by loch (9)
REEDINESS – reversal of I DEER followed by NESS
28 Gizmos DIYers principally obtain in Indiana port (8)
GADGETRY – initial letter of [D]iyers GET in GARY; a quick look online shows that there is some debate, nay, controversy, about whether or not Gary, IN, (which gave us Michael Jackson and his siblings) should be considered a port
29 Lazy time brought forward by new hospital doctor (6)
INTERN – INERT (lazy) with the T brought forward N
DOWN
1 Owned vessel crossing river for trial (8)
HARDSHIP – R in HAD SHIP
2 Live north of African state, missing a dance (7)
BEGUINE – BE on top of (north of) GUINE[a]
3 Sick friend keeping keys without authority(9)
ILLEGALLY – EG (more musical stuff) in ILL ALLY
5 Previously cited supervisors entering sadly on a diet (14)
AFOREMENTIONED – FOREMEN in ON A DIET*
6 Expression of amusement about leaders of creatures at watering-hole (5)
LOCAL – C[reatures] A[t] in LOL
7 Everybody, say, runs over, moving quickly (7)
ALLEGRO – ALL EG R O
8 Trafford town market finally stocking minute young fish (6)
SAMLET – M (minute) in SALE (town in Trafford, Greater Manchester) [marke]T
9 Normal old expedition attendant, one carrying the flag (8-6)
STANDARD-BEARER – STANDARD (normal) BEARER (old expedition attendant)
16 Welsh girl securing a way in for a native of Cagliari? (9)
SARDINIAN – A RD In in SIAN; cue one of the greatest players ever to play the beautiful game (an honorary Sardinian and arguably its most famous son)
17 Generous sum initially spent on young relative (8)
GRANDSON – GRAND (1,000 pounds, so generous sum) S[pent] ON
19 Not on, worker being so casual! (7)
OFFHAND – OFF (not on) HAND (worker)
21 Fellow soldiers outside get up for procession (7)
CORTEGE – GET reversed in CO (fellow) RE (Royal Engineers, soldiers)
22 Broadcasting a set of operas, including Idomeneo at first (6)
AIRING – I[domeneo] in A RING; a hybrid of Wagner and Mozart; I know who I would vote for
24 A fellow European’s place of residence (5)
ABODE – A BOD (fellow) E[uropean]
Joe the Jazzer.
Joe the Jazzer.