More successful gambler (6)
I believe the answer is:
better
This clue might be a double definition.
'more' is the first definition.
(thesaurus)
'successful gambler' is the second definition.
'better' can be an answer for 'gambler' (someone who makes bets is a gambler). I am not certain of the 'successful' bit.
Can you help me to learn more?
(Other definitions for better that I've seen before include "Top" , "More desirable; gambler" , "One making wager; more advantageous" , "recovering from illness" , "Comparatively good" .)