A gambler's accomplice (7)

I believe the answer is:

abetter

'accomplice' is the definition.
(abetter is a kind of accomplice)

'a gambler's' is the wordplay.
'gambler' becomes 'better' (someone who makes bets is a gambler).
'a'+'better'='ABETTER'

(Other definitions for abetter that I've seen before include "accessory" , "person giving encouragement" , "He helps criminal" , "Criminal's assistant" , "one who helps in a crime" .)

I've seen this clue in The Globe and Mail and The Guardian.

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