Superior gambler (6)
I believe the answer is:
better
I believe this clue is a double definition.
'superior' is the first definition.
(better is a kind of superior)
'gambler' is the second definition.
(someone who makes bets is a gambler)
(Other definitions for better that I've seen before include "More effectively" , "More appropriate; gambler" , "Gambler; cured" , "One may lay" , "Speculator" .)