Willing to gamble (4)
I believe the answer is:
game
This clue is a double definition.
'willing' is the first definition.
(game can mean willing to do something)
'gamble' is the second definition.
(I know this)
'to' acts as a link.
(Other definitions for game that I've seen before include "Play or sport" , "Up for it; gamble" , "Prepared" , "Lark" , "Willing; plucky" .)