Not early (4)
I believe the answer is:
late
'not early' is the definition.
('late' is the opposite to 'early')
This is the entire clue.
(Other definitions for late that I've seen before include "Former; behind time" , "No longer alive; tardy" , "Departed - behind time" , "Having bought it" , "Passed on (but still not passed by!)" .)