Mafia bosses (4)
I believe the answer is:
dons
'mafia bosses' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dons that I've seen before include "Academics" , "Puts on -- lecturers" , "British university teachers and Spanish noblemen" , "Assumes" , "University teachers - Mafia bosses" .)