Handle finally on 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 on copper' is the wordplay.
'finally' says to take the final letters.
'on' means one lot of letters go next to another.
'copper' becomes 'cu' (Cu is the chemical symbol for copper).
The last letter of 'handle' is 'e'.
'e' put after 'cu' is 'CUE'.
(Other definitions for cue that I've seen before include "line in speech" , "Hint, prompt" , "Sports implement" , "signal to come on" , "Sign" .)