Stopper; Irish city (4)
I believe the answer is:
cork
I believe this clue is a double definition.
'stopper' is the first definition.
(I know that stopper can be written as cork)
'irish city' is the second definition.
(I've seen this before)
(Other definitions for cork that I've seen before include "Tree bark from the South of Ireland?" , "Type of bark; seal" , "Tree used in bottling" , "Bottle-stopper for a southern city" , "stop" .)