Bitter cop leaving work early (4)
I believe the answer is:
cold
'bitter' is the definition.
(similar in meaning)
'cop leaving work early' is the wordplay.
'leaving' is a deletion indicator.
'work' becomes 'op' (operation, work done in an operating theatre).
'early' becomes 'old' (similar in meaning).
'cop' with 'op' taken away is 'c'.
'c'+'old'='COLD'
(Other definitions for cold that I've seen before include "Unfeeling" , "Biting" , "Unsympathetic" , "Unfriendly" , "Mild viral infection, very common" .)