Curl copper up round edge (5)
I believe the answer is:
crimp
'curl' is the definition.
(crimp is a kind of curl)
'copper up round edge' is the wordplay.
'copper' becomes 'pc'.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'round' is an insertion indicator.
'edge' becomes 'rim' (rim is a kind of edge**).
'pc' in reverse letter order is 'cp'.
'cp' going around 'rim' is 'CRIMP'.
(Other definitions for crimp that I've seen before include "Fold or press into ridges" , "tight lock" , "wave" , "Compress into small folds or ridges" , "Bend into shape" .)