Unspoilt old city in South African region (7)
I believe the answer is:
natural
'unspoilt' is the definition.
(I've seen this before)
'old city in south african region' is the wordplay.
'old city' becomes 'ur' (ancient city state).
'in' is an insertion indicator.
'south african region' becomes 'natal' (I've seen this before).
'ur' put into 'natal' is 'NATURAL'.
(Other definitions for natural that I've seen before include "Unaffected; unaltered" , "one short of being sharp?" , "Unaffected - native" , "pure" , "Illegitimate" .)