Nobody doesn't finish in time (4)
I believe the answer is:
noon
'time' is the definition.
(I know that noon is a type of hour)
'nobody doesn't finish' is the wordplay.
'nobody' becomes 'no one' (not a single person).
'doesn't finish' means to remove the last letter.
'noone' with its final letter removed is 'NOON'.
'in' acts as a link.
(Other definitions for noon that I've seen before include "A moment of time" , "High time of day?" , "12 pm" , "See 8" , "when PM starts" .)