Crossword Genius

A run past (3)

Ross

I believe the answer is:

ago

'past' is the definition.
(I've seen this before)

'a run' is the wordplay.
'run' becomes 'go' ('go' can be a synonym of 'run').
'a'+'go'='AGO'

(Other definitions for ago that I've seen before include "Previously" , "(Years) before the present time" , "Gone, past, since" , "In past times" , "Time past" .)

I've seen this clue in The Times.
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