No one left unfinished in the middle of the day (4)
I believe the answer is:
noon
'the middle of the day' is the definition.
(I've seen this before)
'no one left unfinished' is the wordplay.
'left unfinished' means to remove the last letter.
'one' with its final letter taken away is 'on'.
'no'+'on'='NOON'
'in' acts as a link.
(Other definitions for noon that I've seen before include "[LUNCHTIME] ?" , "when PM starts" , "12 pm" , "Twelve during daylight" , "The middle of the day" .)