Boss to consider finishing early (4)
I believe the answer is:
stud
'boss' is the definition.
('stud' can be a synonym of 'boss')
'consider finishing early' is the wordplay.
'consider' becomes 'study' ('study' can be a synonym of 'consider').
'finishing early' means to remove the last letter.
'study' with its final letter taken away is 'STUD'.
'to' is the link.
(Other definitions for stud that I've seen before include "Collar-fastener" , "Male horse kept for breeding" , "card game" , "Place of breeding" , "Type of poker, a collar and a farm" .)