Pakistan's largest city (7)
I believe the answer is:
karachi
'pakistan's largest city' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for karachi that I've seen before include "Pakistani city" , "Pakistan's largest city" , "City/port of Pakistan" , "Capital of Pakistan, 1947-59" , "Pakistan's first capital" .)