Virile man becomes boss (4)
I believe the answer is:
stud
I believe this is a double definition.
'virile man' is the first definition.
(I've seen this before)
'boss' is the second definition.
(both can mean a metal decoration)
'becomes' is the link.
(Other definitions for stud that I've seen before include "This farm breeds horses" , "sort of stable" , "Stallion kept for breeding" , "Playboy" , "Horse-breeding place" .)