Much of northern Africa (6)
I believe the answer is:
sahara
'much of northern africa' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sahara that I've seen before include "World's largest sandy area" , "Uncultivated region of north Africa" , "Great African desert" , "North African desert" , "Hottest desert" .)