National language of Pakistan (4)
I believe the answer is:
urdu
'national language of pakistan' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for urdu that I've seen before include "Language used in Pakistan, India" , "Indian language" , "Language spoken by Moslems in Pakistan and India" , "Pakistani language" , "Language akin to Hindi" .)