Rule in gaming over non-members (6)
I believe the answer is:
govern
'rule' is the definition.
('govern' can be a synonym of 'rule')
'in gaming over non-members' is the wordplay.
'in' indicates a hidden word.
'GOVERN' is hidden in the letters of 'gaming over non members'.
(Other definitions for govern that I've seen before include "Rule with authority, perhaps a country" , "Control, determine" , "Exercise authority over a people" , "Check; rule" , "Run" .)