Authoritarianism (7)
I believe the answer is:
tyranny
'authoritarianism' is the definition.
(I know that authoritarianism can be written as tyranny)
This is the entire clue.
(Other definitions for tyranny that I've seen before include "Dominance through threat of punishment and violence" , "Oppression" , "Form of despotism" , "Cruel rulers" , "Cruel and oppressive rule" .)