Refusal to start on time? (4)
I believe the answer is:
noon
'time?' is the definition.
(noon is a kind of time)
'refusal to start on' is the wordplay.
'refusal' becomes 'no'.
'to start' is a charade indicator (letters next to each other).
'no'+'on'='NOON'
(Other definitions for noon that I've seen before include "Twelve during daylight" , "A moment of time" , "High time of day?" , "12 o'clock" , "when PM starts" .)