Stud chief (4)
I believe the answer is:
boss
I believe this is a double definition.
'stud' is the first definition.
(I've seen this before)
'chief' is the second definition.
('boss' can be a synonym of 'chief')
(Other definitions for boss that I've seen before include "Bully" , "(One's) chief" , "One managing" , "Person managing" , "Leader; stud" .)