Very funny fat early protestant (7)
I believe the answer is:
lollard
'early protestant' is the definition.
(Lollards were a pre-Reformation Christian movement)
'very funny fat' is the wordplay.
'very funny' becomes 'lol' (internet acronym for laugh out loud).
'fat' becomes 'lard' (lard is a kind of fat).
'lol'+'lard'='LOLLARD'
(Other definitions for lollard that I've seen before include "Radical Christian" , "Follower of John Wycliffe" , "Follower of John Wyclif" , "religious reformer" , "Wycliffite" .)