Language in old city said to be enough (4)
I believe the answer is:
urdu
'language' is the definition.
(Urdu is an example)
'old city said to be enough' is the wordplay.
'old city' becomes 'ur' (ancient city state).
'said' indicates a 'sounds like' (homophone) clue.
'to be enough' becomes 'do' (to do can mean to be sufficient for a task).
'do' is a homophone of 'du'.
'ur'+'du'='URDU'
'in' is the link.
(Other definitions for urdu that I've seen before include "Form of Hindustani" , "Indic language written in Persian script" , "Asian language written in Arabic script" , "Language spoken by Moslems in Pakistan and India" , "Language akin to Hindi" .)