Ancient city originally developing universal language (4)
I believe the answer is:
urdu
'language' is the definition.
(Urdu is an example)
'ancient city originally developing universal' is the wordplay.
'ancient city' becomes 'ur' (ancient Sumerian city state).
'originally' suggests taking the first letters.
The initial letters of 'developing universal' is 'du'.
'ur'+'du'='URDU'
(Other definitions for urdu that I've seen before include "Sub-continental language" , "speech" , "Pakistani tongue" , "Language spoken by Moslems in Pakistan and India" , "An official language of Pakistan related to Hindi" .)