Monsieur with help, servant (4)
I believe the answer is:
maid
'servant' is the definition.
(maid is a kind of servant)
'monsieur with help' is the wordplay.
'monsieur' becomes 'm'.
'with' is a charade indicator (letters next to each other).
'help' becomes 'aid' ('aid' can be a synonym of 'help').
'm'+'aid'='MAID'
(Other definitions for maid that I've seen before include "Female domestic servant" , "Serving girl" , "Damsel" , "employee" , "Young woman - servant" .)