Study with a college head (4)
I believe the answer is:
dean
'college head' is the definition.
(I've seen this before)
'study with a' is the wordplay.
'study' becomes 'den' (den can mean an office or study).
'with' means one lot of letters goes inside another.
'den' going around 'a' is 'DEAN'.
(Other definitions for dean that I've seen before include "Head of e.g. faculty" , "A senior clergyman - Swift was one" , "school head" , "Churchman" , "James ..., film actor" .)