Mother with donkey stopped by copper in capital (8)
I believe the answer is:
damascus
'capital' is the definition.
(capital of Syria)
'mother with donkey stopped by copper' is the wordplay.
'mother' becomes 'dam' (female parent of an animal).
'with' means one lot of letters go next to another.
'donkey' becomes 'ass' (ass is a term for a donkey).
'stopped by' means one lot of letters goes inside another (I've seen this in other clues).
'copper' becomes 'cu' (chemical symbol).
'ass' enclosing 'cu' is 'ascus'.
'dam'+'ascus'='DAMASCUS'
'in' is the link.
(Other definitions for damascus that I've seen before include "capital city" , "Middle East capital" , "Syrian capital" , "Pauline conversion on the road to here" , "ancient city" .)