Contract workers perhaps losing rag in nightmare
I believe the answer is:
hit men
'perhaps losing rag in nightmare' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'contract workers' is the wordplay.
'contract' becomes 'hit' (I am not sure about this - if you are sure you should believe this answer much more).
'workers' becomes 'men' (man is a kind of worker).
'hit'+'men'='HIT MEN'
Can you help me to learn more?
(Other definitions for hit men that I've seen before include "Modern paid assassins" , "Modern hired assassins" , "Hired killers" .)