Fault-finding ruined the chat before work (7,3)
I believe the answer is:
hatchet job
'fault-finding' is the definition.
(article attacking someone)
'ruined the chat before work' is the wordplay.
'ruined' indicates anagramming the letters.
'before' is a charade indicator (letters next to each other).
'work' becomes 'job' (job is a kind of work).
'the'+'chat'='thechat'
'thechat' with letters rearranged gives 'hatchet'.
'hatchet'+'job'='HATCHET JOB'
(Other definitions for hatchet job that I've seen before include "devastating attack" , "Fierce written attack" , "Destructive critical attack" , "Malicious verbal or written attack" , "Given destructive piece of criticism" .)