Could mum have a bit of fun with him? (3)
I believe the answer is:
man
'him?' is the definition.
(thesaurus)
'could mum have a bit of fun' is the wordplay.
I cannot really see how this works, but
'mum' could be 'ma' (both can mean mother) and 'ma' is found in the answer.
A single letter 'n' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
'with' acts as a link.
Can you help me to learn more?
(Other definitions for man that I've seen before include "The most destructive and polluting animal" , "Bloke" , "Dude" , "Provide with crew" , "Where people compete to win TT" .)