Severe criticism of chopper's role (7,3)
I believe the answer is:
hatchet job
'severe criticism' is the definition.
'chopper's role' is the wordplay.
'chopper' becomes 'hatchet' (something which 'chops').
'role' becomes 'job'.
'hatchet'+'job'='HATCHET JOB'
'of' acts as a link.
(Other definitions for hatchet job that I've seen before include "Given destructive piece of criticism" , "Destructive critical attack" , "what Washington admitted?" , "Fierce written attack" , "Malicious verbal or written attack" .)