Tribal chief as executioner? (7)
I believe the answer is:
headman
I believe this clue is a double definition.
'tribal chief' is the first definition.
('headman' can be a synonym of 'tribal chief')
'executioner?' is the second definition.
(headman is a kind of executioner)
'as' is the link.
(Other definitions for headman that I've seen before include "Chieftain" , "Village chief" , "Leader" , "Boss" .)