Old religious warrior, more primitive, around S Africa (8)
I believe the answer is:
crusader
'old religious warrior' is the definition.
'more primitive around s africa' is the wordplay.
'more primitive' becomes 'cruder' ('crude' can be a synonym of 'primitive').
'around' means one lot of letters goes inside another.
's africa' becomes 'sa'.
'cruder' enclosing 'sa' is 'CRUSADER'.
(Other definitions for crusader that I've seen before include "Campaigner -- rude scar (anag)" , "Vigorous campaigner" , "An old soldier" , "Christian warrior" , "Medieval expeditionary" .)