Spray first of schnapps on prude (5)
I believe the answer is:
sprig
'spray' is the definition.
(I've seen this before)
'first of schnapps on prude' is the wordplay.
'first of schnapps' becomes 's' (1st letter of 'schnapps').
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'prude' becomes 'prig' (I've seen this before).
's'+'prig'='SPRIG'
(Other definitions for sprig that I've seen before include "Small nail without a head" , "related to Spike and Brad" , "Small stem taken from a bush or plant" , "Youth" , "Small stem bearing flowers" .)