Foolish person, fan with nothing on (7)
I believe the answer is:
buffoon
'foolish person' is the definition.
(I've seen this before)
'fan with nothing on' is the wordplay.
'fan' becomes 'buff' ('buff' can be a synonym of 'fan').
'with nothing' becomes 'o' (I've seen this in other clues).
'buff'+'o'+'on'='BUFFOON'
(Other definitions for buffoon that I've seen before include "'Clown, fool (7)'" , "comic" , "Jester" , "Ridiculous person" , "Foolish person" .)