This QC was so well devised that it led me the wrong way around most of the clues. I gave up on any thought of timings and settled down to work through and enjoy the cleverness of the clues. I struggled most trying to finish in the NE but made it in the end.
For Jackkt (and anyone else) who has mentioned problems with reading the font, I would point out that the word in 3dn is BURN (not bum).
4. Eccentric drunken widower giving out whiskey (6)
WEIRDO - anagram (drunken) of wIDOWER - without whiskey (W).
7. Sell death-trap missing odd parts for prolonged quarrel (8)
VENDETTA - sell (VEND), d(E)a(T)h (T)r(A)p.
8. What tea does at home — fine with us English (6)
INFUSE - at home (IN), fine (F) with us (US), English (E).
9. Current desperate before court is not going straight (8)
INDIRECT - current (IN - vogue), desperate (DIRE - bad), court (CT).
10. Notice small storage container (4)
SPOT - small (S), storage container (POT).
12. Chest bone found in tumulus near the end (8)
MORIBUND - chest bone (RIB) found in tumulus (MOUND).
15. Star rode about in open-top car (8)
ROADSTER - anagram (about) of STAR RODE.
18. Chairmen regularly feel concern (4)
CARE - (C)h(A)i(R)m(E)n.
20. Discovering strange and flashy jewellery (8)
RUMBLING (finding out about) - strange (RUM), flashy jewellery (BLING).
22. Cast embracing chap showing compassion (6)
HUMANE - cast (HUE/shade/colour) around chap (MAN).
23. Dislike a particular edition (8)
AVERSION - a (A), particular edition (VERSION).
24. A key opening for period before Christmas (6)
ADVENT - a (A), key (D - music), opening (VENT).
1. Be inclined to be skinny (4)
LEAN - double definition.
LEAN - double definition.
2. Hooked cadet did badly (8)
ADDICTED - anagram (badly) of CADET DID.
3. Burn saint concerning a mass (6)
STREAM (this meaning of burn took me ages) - Saint (ST), concerning (RE), a (A), mass (M - as in mass in physics not in a church). COD for doubly confusing me.
4. One serving island in the sea, perhaps (6)
WAITER - island (I) in sea, perhaps/for example (WATER).
5. Intelligence of kinfolk? (4)
INFO - of as in belonging to as in inside the word k(INFO)lk. expertly hidden in plain sight.
6. Creator of grid seen to be twisted (8)
DESIGNER - anagram (to be twisted) of GRID SEEN. I spent a long time trying to fit In an anagram of ‘seen to be'.
11. Advance for the UK’s currency (8)
PROPOUND - for (PRO), UK's currency (POUND).
13. United previously eliminating clubs (3)
ONE - previously (ON)c(E) - omitting clubs (C).
14. Support flogging for a violent reaction (8)
BACKLASH - support (BACK), flogging (LASH - not sure these are really synonymous but by now I’m enjoying the clues too much to quibble).
16. Hard coming in to deal with possibility of trouble (6)
THREAT - hard (H) coming in to deal with (TREAT - eg patient).
17. Sheep, black is a bit of a fast fighter? (6)
RAMJET - sheep (RAM), black (JET). Well, I suppose I’ve heard of 'ramjet' and I’m sure it’s in all the sources but it didn’t leap out at me.
19. Become weaker and pale with little energy (4)
WANE - pale (WAN), little energy (E).
21. Corner quite the opposite of satisfactory (4)
NOOK - the opposite of satisfactory=NO OK. a final devious twist to finish us off - thanks Joker.