Winning gamble — result! (6)
I believe the answer is:
upshot
'result' is the definition.
(I know that result can be written as upshot)
'winning gamble' is the wordplay.
'winning' becomes 'up' (eg being up at half time in football).
'gamble' becomes 'shot' (it's worth a shot).
'up'+'shot'='UPSHOT'
(Other definitions for upshot that I've seen before include "anti-aircraft fire?" , "One killed the albatross" , "issue" , "skier" , "increased exposure" .)