Red Sea nation; capital Khartoum (5)
I believe the answer is:
sudan
This clue is a double definition.
'red sea nation' is the first definition.
(I've seen this in another clue)
'capital khartoum' is the second definition.
(I know that Sudan has the capital city Khartoum)
(Other definitions for sudan that I've seen before include "Region of Africa" , "Us and the African state" , "Recently-split country" , "African country on the Red Sea" , "Country W. of Ethiopia" .)