Boss promises to reimburse academic (8)
I believe the answer is:
studious
'academic' is the definition.
(academic can mean studious or scholarly)
'boss promises to reimburse' is the wordplay.
'boss' becomes 'stud' (both can mean a metal decoration).
'promises to reimburse' becomes 'IOUs' (promises to pay someone back).
'stud'+'ious'='STUDIOUS'
(Other definitions for studious that I've seen before include "with great care" , "Diligent; scholarly" , "Like a good schoolboy" , "Academic, diligent" , "Bookish, sedulous" .)