One move gone (3)
I believe the answer is:
ago
'gone' is the definition.
(eg 'two weeks gone' could mean 'two weeks ago')
'one move' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'move' becomes 'go' (to go is to move).
'a'+'go'='AGO'
(Other definitions for ago that I've seen before include "Previously" , "Time past" , "Back (in time)" , "Gone, past, since" , "Earlier, gone by" .)