Foremost of athletes shot past (3)
I believe the answer is:
ago
'past' is the definition.
(similar in meaning)
'foremost of athletes shot' is the wordplay.
'foremost of' says to take the initial letters.
'shot' becomes 'go' (I've seen this in other clues).
The first letter of 'athletes' is 'a'.
'a'+'go'='AGO'
(Other definitions for ago that I've seen before include "Previously" , "Back (in time)" , "(Years) before the present time" , "Gone, past, since" , "Time past" .)