The Independent editor is exhausted (4)
I believe the answer is:
used
'is exhausted' is the definition.
(exhaust can mean to use up)
'the independent editor' is the wordplay.
'the independent' becomes 'us' (the puzzle setter and their Independent colleagues).
'editor' becomes 'ed' (abbreviation).
'us'+'ed'='USED'
(Other definitions for used that I've seen before include "Previously owned by another" , "Sued, having been employed" , "Not fresh" , "Second-hand - not wasted" , "given employment" .)