Signal given by copper close to scene (3)
I believe the answer is:
cue
'signal' is the definition.
(as in an actor's cue)
'by copper close to scene' is the wordplay.
'by' is a charade indicator (letters next to each other).
'copper' becomes 'cu' (chemical symbol).
'close to' says to take the final letters (the close/ending of).
The final letter of 'scene' is 'e'.
'cu' next to 'e' is 'CUE'.
'given' acts as a link.
(Other definitions for cue that I've seen before include "Actor's line to remind another" , "strike" , "signal to come on" , "Used in snooker and on stage" , "Signal to begin - tapered stick" .)