Young lady's help accepted by chaps (6)
I believe the answer is:
maiden
'young lady's' is the definition.
(maiden is a kind of young lady)
'help accepted by chaps' is the wordplay.
'help' becomes 'aid' (synonyms).
'accepted by' is an insertion indicator (inserted letters are accepted).
'chaps' becomes 'men' (chap means a man).
'aid' put inside 'men' is 'MAIDEN'.
(Other definitions for maiden that I've seen before include "See 3" , "No runs for the unmarried lady's over" , "No runs are scored from this - young girl" , "To the rear (of a ship)" , "First, inaugural" .)