She may be a bit of a fool (3)
I believe the answer is:
flo
'a fool' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I don't see?
'she may be a bit of' is the wordplay.
'she may' becomes 'fl' (I can't explain this - if you can you should believe this answer much more).
'be a bit' suggests taking the first letters (I've seen 'a bit of' mean this).
The first letter of 'of' is 'o'.
'fl'+'o'='FLO'
Can you help me to learn more?
(Another definition for flo that I've seen is " Nightingale".)