Argument coming from retired coppers, perhaps (8)
I believe the answer is:
exchange
'argument' is the definition.
(I've seen this before)
'retired coppers perhaps' is the wordplay.
'retired' becomes 'ex' (prefix meaning former or onetime).
'coppers perhaps' becomes 'change' (I've seen this before. I am not sure about the 'perhaps' bit.).
'ex'+'change'='EXCHANGE'
'coming from' acts as a link.
Can you help me to learn more?
(Other definitions for exchange that I've seen before include "truck" , "Barter; switch" , "Give one thing and get another back" , "Brief argument" , "Short conversation or argument" .)