Ruler I haven't clued cryptically? (4,3,8)
I believe the answer is:
ivan the terrible
'ruler' is the definition.
(16th-century tsar of Russia)
I don't understand how the remainder of the clue works.
(Other definitions for ivan the terrible that I've seen before include "First tsar of all Russia" , "despot" , "Russian tsar" , "Dreadful ruler" , "Dictator" .)