Boss working hard to clear debts (4)
I believe the answer is:
stud
'boss' is the definition.
(both can mean a metal decoration)
'working hard to clear debts' is the wordplay.
'working hard' becomes 'studious' (I've seen this before).
'to clear' indicates named letters should be taken away.
'debts' becomes 'IOUs' (promises to pay debts).
'studious' with 'ious' taken out is 'STUD'.
(Other definitions for stud that I've seen before include "Ladies' man?" , "Specified arrangement" , "Decorative round-headed nail" , "pin" , "Lothario" .)