Criminally assists as wager is accepted (5)
I believe the answer is:
abets
'criminally assists' is the definition.
(as in aiding and abetting a criminal)
'as wager is accepted' is the wordplay.
'wager' becomes 'bet' (synonyms).
'is accepted' indicates putting letters inside.
'as' going around 'bet' is 'ABETS'.
(Other definitions for abets that I've seen before include "Assists dealer, say" , "Assists or encourages" , "Helps (someone to commit crime)" , "Gives support" , "Aids in wrong-doing" .)