Fifth word of "American Pie" (3)
I believe the answer is:
ago
'fifth word of american pie' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ago that I've seen before include "Back (in time)" , "Gone, past, since" , "(Years) before the present time" , "Earlier, gone by" , "In past times" .)