Handle finally attached to copper pot with this (3)
I believe the answer is:
cue
'pot with this' is the definition.
(used to pot balls in snooker, pool etc)
'handle finally attached to copper' is the wordplay.
'finally' says to take the final letters.
'attached to' says to put letters next to each other.
'copper' becomes 'cu' (chemical symbol).
The final letter of 'handle' is 'e'.
'e' after 'cu' is 'CUE'.
(Other definitions for cue that I've seen before include "Signal to players" , "Actor's words" , "Hint on stage" , "Sign" , "Prompt; reminder" .)