Wager includes fine form of profit (7)
I believe the answer is:
benefit
'profit' is the definition.
('benefit' can be a synonym of 'profit')
'wager includes fine form' is the wordplay.
'wager' becomes 'bet' ('bet' can be a synonym of 'wager').
'includes' is an insertion indicator.
'form' indicates an anagram.
'fine' is an anagram of 'nefi'.
'bet' placed around 'nefi' is 'BENEFIT'.
'of' is the link.
(Other definitions for benefit that I've seen before include "Fine bet (anag)" , "Financial assistance" , "Fringe - -" , "Advantage or profit gained from something" , "Advantage or blessing" .)