Beer cask is found in North African city (5)
I believe the answer is:
tunis
'north african city' is the definition.
(capital of Tunisia)
'beer cask is' is the wordplay.
'beer cask' becomes 'tun' (large container for beer).
'tun'+'is'='TUNIS'
'found in' acts as a link.
(Other definitions for tunis that I've seen before include "N African port" , "Tom, Dick or Harry" , "North African city" , "Mediterranean capital and port" , "I stun (anag) - port and capital" .)