Copper first to be seen in the nick (3)
I believe the answer is:
cut
'nick' is the definition.
(thesaurus)
'copper first to be seen in the' is the wordplay.
'copper' becomes 'cu' (Cu is the chemical symbol for copper).
'first to be seen in' suggests taking the first letters.
The first letter of 'the' is 't'.
'cu'+'t'='CUT'
(Other definitions for cut that I've seen before include "Excise" , "Divide; intersect" , "Incision; reduce" , "Reap" , "Slice, chop" .)