A win? Encore! (5)

I believe the answer is:

again

'encore' is the definition.
(thesaurus)

'a win?' is the wordplay.
'win?' becomes 'gain' (win is a kind of gain**).
'a'+'gain'='AGAIN'

(Other definitions for again that I've seen before include "Moreover - a second time" , "Repeatedly" , "One more time, encore" , "Furthermore" , "Anew" .)

I've seen this clue in The Telegraph.

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