Old city vehicle taking hours, long time (8)
I believe the answer is:
carthage
'old city' is the definition.
(I've seen this before)
'vehicle taking hours long time' is the wordplay.
'vehicle' becomes 'cart' (cart is a kind of vehicle).
'taking' is a charade indicator (letters next to each other).
'hours' becomes 'h'.
'long time' becomes 'age' ('age' can be a synonym of 'long time').
'cart'+'h'+'age'='CARTHAGE'
(Other definitions for carthage that I've seen before include "It fought the Punic wars against ancient Rome" , "Ancient Tunisian city" , "Dido was queen of this ancient city in N Africa" , "Hannibal's home city" , "Ancient N. African city" .)