Drink with retired setter maybe after installing old copper insulator (7,8)
I believe the answer is:
draught excluder
'installing old copper insulator' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'drink with retired setter maybe' is the wordplay.
'drink' becomes 'draught' (draught is a kind of drink).
'with' is a charade indicator (letters next to each other).
'retired setter maybe' becomes 'excluder' (I am not sure about this - if you are sure you should believe this answer much more).
'draught'+'excluder'='DRAUGHT EXCLUDER'
'after' is the link.
Can you help me to learn more?
(Other definitions for draught excluder that I've seen before include "that might stop delivery of beer?" , "Solution to current problem" , "Current bar" .)