Pakistan's official language (4)
I believe the answer is:
urdu
'pakistan's official language' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for urdu that I've seen before include "An official language of Pakistan related to Hindi" , "Indic language written in Persian script" , "Analyse and develop (an idea) in detail" , "Asian language written in Arabic script" , "Channel to north of Isle of Wight" .)