Exceed as a gambler (6)
I believe the answer is:
better
I believe this clue is a double definition.
'exceed' is the first definition.
(bettering is a kind of exceeding)
'a gambler' is the second definition.
(someone who makes bets is a gambler)
'as' acts as a link.
(Other definitions for better that I've seen before include "Not as bad" , "showing improvement" , "More desirable; gambler" , "person making use of 43 [TOTE]" , "Speculator" .)