Entrance examination abandoned by university (4)
I believe the answer is:
adit
'entrance' is the definition.
(I've seen this before)
'examination abandoned by university' is the wordplay.
'examination' becomes 'audit' (I've seen this before).
'abandoned by' is a deletion indicator.
'university' becomes 'u'.
'audit' with 'u' taken out is 'ADIT'.
(Other definitions for adit that I've seen before include "Passageway into a mine" , "Horiz. mine entrance" , "Taking passage" , "Horizontal mine passage" , "Da, it is a mine entrance" .)