After the buzzer (4)
I believe the answer is:
late
'after the buzzer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for late that I've seen before include "Unpunctual or dead (4)" , "Still to come - already gone!" , "Dead or behind time" , "Far on in the day" , "on time? Not quite" .)