Boss, leader (5)
I believe the answer is:
chief
I believe this clue is a double definition.
'boss' is the first definition.
(I know that boss can be written as chief)
'leader' is the second definition.
(I know that chief is a type of leader)
(Other definitions for chief that I've seen before include "Tribal head" , "Leader, head" , "cardinal" , "Head of a native American tribe" , "Principal" .)