Copper, teetotal, in Gateshead being hurtful (7)
I believe the answer is:
cutting
'hurtful' is the definition.
(I've seen this before)
'copper teetotal in gateshead' is the wordplay.
'copper' becomes 'cu' (chemical symbol).
'teetotal' becomes 'tt' (abbreviation).
'gateshead' becomes 'g' (head letter of 'gates').
'cu'+'tt'+'in'+'g'='CUTTING'
'being' is the link.
(Other definitions for cutting that I've seen before include "Incisive" , "something for propagation" , "Making an incision" , "(Of a remark) hurtful" , "Channel" .)