Fellow attorney’s last bit of work (4)
I believe the answer is:
coda
'last bit of work' is the definition.
(final part of a musical work)
'fellow attorney's' is the wordplay.
'fellow' becomes 'co' (eg a co-worker is a fellow worker).
'attorney' becomes 'DA' (District Attorney).
'co'+'da'='CODA'
(Other definitions for coda that I've seen before include "noted conclusion" , "Word that modifies" , "bit at the end" , "Passage of piece of music added to the end" , "Final section" .)