Restrain pointer, very loud, circling copper (8)
I believe the answer is:
handcuff
'restrain' is the definition.
(I've seen this before)
'pointer very loud circling copper' is the wordplay.
'pointer' becomes 'hand' (hand is a kind of pointer).
'very loud' becomes 'ff' (musical abbreviation).
'circling' means one lot of letters goes inside another (circling can mean going around or containing).
'copper' becomes 'cu' (chemical symbol).
'hand'+'ff'='handff'
'handff' going around 'cu' is 'HANDCUFF'.
(Other definitions for handcuff that I've seen before include "Put bracelets on" , "Restrain (one arrested)" , "Restraint" , "Restrict movement" , "Manacle" .)