Day of month and year (4)
I believe the answer is:
date
'day of month and year' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for date that I've seen before include "Particular time of event - fruit" , "A social appointment - check calendar" , "The fruit for a social engagement" , "Oval fruit" , "Small fruit or social appointment" .)