Domineering person (8)
I believe the answer is:
autocrat
'domineering person' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for autocrat that I've seen before include "Dictatorial person" , "Person with unlimited power, kind of dictator" , "Dictatorial type" , "Domineering person" , "Despot, tyrant" .)