Turned over in pontoon, I sacrificed fortune needed to win here (6)
I believe the answer is:
casino
'to win here' is the definition.
(where a gambler might win money)
'turned over in pontoon i sacrificed fortune' is the wordplay.
'turned over' says the letters should be written backwards.
'in' indicates a hidden word.
'onisac' is hidden within 'pontoon i sacrificed fortune'.
'onisac' in reverse letter order is 'CASINO'.
'needed' is the link.
(Other definitions for casino that I've seen before include "Gambling establishment" , "--- Royale (Fleming)" , "Building for gambling" , "Scorsese film - Bond film if "royale"" , "Where gambling may be seen" .)