Help make a wager (4)
I believe the answer is:
abet
'help' is the definition.
(I've seen this before)
'a wager' is the wordplay.
'wager' becomes 'bet' (synonyms).
'a'+'bet'='ABET'
'make' is the link.
(Other definitions for abet that I've seen before include "Aid as in committing crime" , "Incite or encourage" , "Incite (to commit an offence)" , "Help in wrongdoing" , "Egg on" .)