Don't allow a bachelor to have a bit of fun (3)
I believe the answer is:
ban
'don't allow' is the definition.
(I've seen this in another clue)
'a bachelor to have a bit of fun' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is present in the answer.
'bachelor' could be 'b' (abbreviation e.g. BA=Bachelor of Arts) and 'b' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ban that I've seen before include "'Forbid, prohibit (3)'" , "Hungarian governor < to forbid" , "Veto" , "Officially prohibit" , "Bar, prohibition" .)