Renounce study by university finally (4)
I believe the answer is:
deny
'renounce' is the definition.
(denying is a kind of renouncing)
'study by university finally' is the wordplay.
'study' becomes 'den' (term for a study or office).
'by' means one lot of letters go next to another.
'finally' indicates one should take the final letters.
The last letter of 'university' is 'y'.
'den'+'y'='DENY'
(Other definitions for deny that I've seen before include "Refuse; repudiate" , "Negate" , "Refuse to acknowledge" , "Refuse to admit the truth" , "Refute, contradict" .)