Concentrate solution
by Kegler

In eight squares, two of the letters in M-I-L-K are supplied by the Across entry, the other two are supplied by the Down.  The result, as described by 23 Across, is CONDENSED MILK.

Concentrate solution grid

Across
1TRACK MEET (MARKET ETC anag)
7SET + H
11DROPS ANCHOR (PRO HAD SCORN anag)
12K(IS + S)ING
14BAL + MY (LAB rev)
16E + L + BOWlER
17DE(M)IT (TIED rev)
18SOBER (ROBES anag)
21I'D + YLS (SLY rev)
22LORE + N
23CONDENSED MILK
26WEEKLY ("WEAKLY" hom)
27EL(E)M + I
30S(T)ING
31B(R)AN
32S(IDEW)ALK (WIDE anag)
37EM + IR (rev)
38SpY + SOPS
39S + PEAR + MIN + TOIL (30 seconds = "half MINute")
40ST(A)Y
41ESTIMATES (hidden)
Down
1TAL(MUD + I)C
2RE(ST)ED
3C + RIB
4LI(ONE'S)St
5ESTE (TEES anag)
6TAB + LE + TEN + NIS (rev)
7SNUB (rev)
8THAW (WHAT anag)
9H(OK + I)ER
10DR + Y + RUN (NURses rev)
13GR(OUNDT)ACKLE (DONUT anag)
14BO(S)OM
15ALKYNES (KEN LAY'S anag)
19BASS + I
20B(R)IERS
24D(IMME)R (MIME anag)
25KINE + SIS
26WISEST (hidden)
27E(G + G)YOLK (YOKEL anag)
28MAG + P(I)E (GAM rev)
29W + IMPS
33DIE + T
34WAR + Y
35M(I)ENS
36A,S + IA