Solution to 18D has been deliberately left unsolved and is to be answered by a non-regular / novice commenter, with proper annotation. Those who have answered earlier in the week, please give others a chance.
Open for anyone to answer, if not solved by 1 PM.
ACROSS
12 Getting tailless dog in south eastern corral (8) SECURING {SE}{CUr}{RING}
13 Hit wound violently in suspense story (8) WHODUNIT*
15 Get dressed, perhaps, and be Nero, fiddling... (6) ENROBE*
17 Most crazy to get a Chinese body part (7) STOMACH {MOST*}{A}{CH}
19 What a groom might get for painting once again? (3,4) NEW COAT [DD]
22 Marshal Omar carries word of peace (6) SHALOM [T]
26 Person carrying one's moniker, but may be unrelated (8) NAMESAKE [CD]
28 Once saucy ace (6) EXPERT {EX}{PERT}
30 Neurologist possesses some continental currency (4) EURO [HIPS]
31 Street commonly mentioned by Perry Mason in model law (5) DELLA [T]
32 Place to buy half-shorts with Papa (4) SHOP {SHOrts}{P}
DOWN
1 Moist place to store water on top of pitcher (4) DAMP {DAM}{Pi...r}
2 OK, dimes are scattered around hotel in Arab chief's territory (8) SHEIKDOM {OK+DIMES}* over {H}
3 Gross profit from liquor after March, in short (6) MARGIN {GIN}{<=>{MARch}
6 One may reflect... MOM or MUM looks the same in this (6) MIRROR [DBE]
7 Logo in the heart of designer (4) SIGN [HIPS]
14 Jerk's tenure in America (5) HITCH [DD]
16 Snake on road panel (5) BOARD {BOA}{RD}
18 Orders, with new note on first of September (8) C?M?A?D? (Addendum - COMMANDS {COMMA}{N}{D}{Se...r} - See comments)
20 Least expensive animal in box (8) CHEAPEST {CHE{APE}ST}
21 Announcement made by tennis referee at beginning of match between belligerent players (4,3) LOVE ALL [CD]
23 Tell untruth before owl flies and go underground, perhaps (3,3) LIE LOW {LIE}{OWL*}
25 General method to get elbow room (6) LEEWAY {LEE}{WAY}
27 Be next to rejected musical instrument (4) ABUT<=
29 Moor is back in space (4) ROOM<=
Reference List
South = S, Island = I, New = N, South Eastern = SE, Chinese = CH, Papa = P, Hotel = H, King = K, Son = S, Road = RD, Note = D