Study occupied by a university official (4)
I believe the answer is:
dean
'university official' is the definition.
(I've seen this in another clue)
'study occupied by a' is the wordplay.
'study' becomes 'den' (term for a study or office).
'occupied by' is an insertion indicator (inserted letters occupy or enter the word).
'den' going around 'a' is 'DEAN'.
(Other definitions for dean that I've seen before include "Glos. forest; Dixie ---, Everton hero" , "College official" , "FILMSTAR" , "Resident fellow" , "Ice dancer" .)