Examine boss on the end of slavery (5)
I believe the answer is:
study
'examine' is the definition.
(synonyms)
'boss on the end of slavery' is the wordplay.
'boss' becomes 'stud' (both can mean a metal decoration).
'on' says to put letters next to each other.
'the end of' suggests the final letters.
The last letter of 'slavery' is 'y'.
'stud'+'y'='STUDY'
(Other definitions for study that I've seen before include "Contemplate" , "Read up - academic work" , "Read to learn" , "See 11" , "Writing-room" .)