Another win following ace (5)
I believe the answer is:
again
'another' is the definition.
(I've seen this before)
'win following ace' is the wordplay.
'win' becomes 'gain' ('gain' can be a synonym of 'win'**).
'following' means one lot of letters go next to another.
'ace' becomes 'a'.
'gain' after 'a' is 'AGAIN'.
(Other definitions for again that I've seen before include "Repeatedly" , "Furthermore" , "'Another time, once more (5)'" , "return" , "Anew" .)