Its capital is Khartoum (5)
I believe the answer is:
sudan
'its capital is khartoum' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sudan that I've seen before include "Country south of Egypt" , "Region of Africa" , "Country bordering the Red Sea" , "African country on the Red Sea" , "Country W. of Ethiopia" .)