SOS! solution
by Kegler

Six entries have a word meaning “help” added before entry in the grid, as explained by the phrase
SOME EXTRA HELP at 25 Across.  The parsings show these added words in curly brackets.  

SOS! solution grid

Across
1ACCEPTED ("EXCEPTED" hom)
6PLATO (A PLOT anag)
9TEA ("TEE" hom)
10IRON + M{AID}E + N
12L(E)T
15MO(R) + BID
17HA(MaLE)T
18PRO(M)S
20SPY (1st letters)
21RIBS (2 defs)
23CLUBS (2 defs)
24A(C)CUSE (SAUCE anag)
25SOME EXTRA HELP
27TRACES (CRATES anag)
29VI(P)ER
32ASEA ("A CEE" hom)
33MAD (DAM rev)
35PR(I)ES
36S{HINT}Ow
37ORDEAL (LOADER anag)
39AS + K
40NECTARINES (CANS ENTIRE anag)
41TOE ("TOW" hom)
42D + WELT
43B{ASSIST}S
Down
1A + TLAS (SALT rev)
2CA(TH)Y
3PROMISEES (POEMS RISE anag)
4TOO + L + B + OX
5ENMESH (hidden)
6PAR (RAP rev)
7rADIOS
8ONES(T,E)P (OPENS anag)
11MOTH (hidden)
13EX + P(LORE)R
14B(ARB)E{CUE}D
16BRACHIATE (REACH A BIT anag)
19M(IS){LEAD}S
22SC + AVENGES
25S{TIP} + END
26RE(S)IGNS
28DAHLIA (ALI HAD anag)
30CIRClE
31TSAR (rev hidden)
33MO(A)TS
34DIK(E)S (SKID rev)
38mEATs