Old copper ran off with stitch (4)
I believe the answer is:
darn
'stitch' is the definition.
(I've seen this before)
'old copper ran off' is the wordplay.
'old copper' becomes 'd'.
'off' is an anagram indicator.
'ran' with letters rearranged gives 'arn'.
'd'+'arn'='DARN'
'with' is the link.
(Other definitions for darn that I've seen before include "Repair holes by sewing" , "Mend by stitching - damn!" , "Mend with stitches" , "Mend with a needle" , "Mend (e.g. socks)" .)