Encourage in crime for a wager (4)
I believe the answer is:
abet
'encourage in crime' is the definition.
(I've seen this in another clue)
'a wager' is the wordplay.
'wager' becomes 'bet' (synonyms).
'a'+'bet'='ABET'
'for' is the link.
(Other definitions for abet that I've seen before include "Make good" , "Incite, help" , "Help in wrongdoing" , "Encourage (offence)" , "Urge on, help" .)