Willing to bet (4)
I believe the answer is:
game
I believe this clue is a double definition.
'willing' is the first definition.
(thesaurus)
'bet' is the second definition.
(gaming is a kind of betting)
'to' is the link.
(Other definitions for game that I've seen before include "football, perhaps" , "Courageous < pheasants, perhaps" , "Willing to try" , "See 3" , "Ducks and drakes, for example" .)