Maybe dad having a bit of fun with mum (3)
I believe the answer is:
man
'mum' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'maybe dad having a bit of fun' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is found within the answer.
A single letter 'm' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
'with' is the link.
Can you help me to learn more?
(Other definitions for man that I've seen before include "Isle of . . ., . . . o' war" , "Board token; husband" , "Staff the island" , "Isle of -; chess piece" , "Valet" .)