Buzzer's favaurite author Agatha Christie?
ACROSS
1 - Novel way a countdown is headed (7,4) - TOWARDS ZERO [DD]
9 - Direly injured sea turtle (6) - RIDLEY*
10 - It makes one!? (5,3) - SPILT NEO {SPLIT (ONE*)} (Addendum - SHIFT KEY [CD] - See comments)
11 - Gown a date took off in speech (5) - DRESS {adDRESS}
12 - Natural grain, ground and fed to only child (7) - ORGANIC {O}{GRAIN*}{C}
13 - Patent, a clear way to protect one feels (8) - TENTACLE [T]
15 - Seek advice to part with company for one affront (6) - INSULT {1}{coNSULT}
16 - High class fur is still functional (6) - USABLE {U}{SABLE}
18 - Animal planet, observe outsiders, is wild (8) - ANTELOPE {PLANET+ObservE}*
21 - Oddly such info is perhaps cyberpunk (3-2) - SCI-FI {SuCh InFo Is}
22 - Characteristic of one with a beer gut (5,3) - BELLY OUT [CD] Like me and.......
23 - American state with an alternate form of gold? (6) - OREGON {OR}EGON Anno pending (Addendum - OREGON [TD] - See comments)
24 - Book dog that is a mute spectator (4,7) - DUMB WITNESS {DUMB} {WITNESS}
DOWN
2 - Anoint one English saint as most glib (7) - OILIEST {OIL}{I}{E}{ST}
3 - Sailor on ship went round edge of bay or gulf (5) - ABYSS {A}{BaY}{SS} (Addendum - {AB}{baY}{SS} - See comments)
4 - Do away with leaderless top sides in turmoil (7) - DISPOSE {tOP+SIDES}*
5 - Somehow I get one to pack enthusiasm and show the spirit (9) - ZEITGEIST {I+GET+1+ZEST}*
6 - Ultimate aim of a TV show (7) - RATINGS [CD]
7 - Violinists crowd seen after a play (8,5) - FIDDLERS THREE {FIDDLERS} {THREE}
8 - Christie’s man auctioned off our helicopter (7,6) - HERCULE POIROT*
14 - Many tend to crash and burn, yet it leaves no trace (5,4) - CLEAN BOMB {C}{LEAN} {BOMB}
17 - New baubles for a smart woman (3,4) - BAS BLEU*
18 - Plant found in vacant highlands (7) - ACANTHI [T]
19 - Hangs around to see rites administered (7) - LOITERS {LO}{RITES*}
21 - Look down on 20 changing direction finally (5) - SCORN SCOR(-e+n)N