After firm kiss, groom's dandy (7)
I believe the answer is:
coxcomb
'dandy' is the definition.
(both can mean a vain man)
'after firm kiss groom's' is the wordplay.
'after' is a charade indicator (letters next to each other).
'firm' becomes 'co' (a firm is a company).
'kiss' becomes 'x' (X can represent a kiss).
'groom' becomes 'comb' (combing is a way of grooming oneself).
'co' next to 'x' is 'cox'.
'cox'+'comb'='COXCOMB'
(Other definitions for coxcomb that I've seen before include "Red crest on the head of the domestic fowl" , "Fleshy red crest on a cock's head" , "rather vain fellow" , "Fop - fleshy outgrowth on a cockerel's head" , "Conceited dandy" .)