African king is going the wrong way (5)
I believe the answer is:
tutsi
'african' is the definition.
(the Tutsi are an African ethnic group)
'king is going the wrong way' is the wordplay.
'king' becomes 'tut' (King Tut, short for Tutankhamun).
'going the wrong way' shows that the letters should be reversed in order.
'is' written backwards gives 'si'.
'tut'+'si'='TUTSI'
(Other definitions for tutsi that I've seen before include "African tribe" , "Member of a Bantu people of Rwanda and Burundi" , "Bantu speaking people of Rwanda and Burundi" , "Rwanda tribe member" , "Rwandan group" .)