When morning is over (4)
I believe the answer is:
noon
'when morning is over' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for noon that I've seen before include "High time of day?" , "when only mad dogs go out?" , "Twelve o'clock, midday" , "The middle of the day" , "A moment of time" .)