Tyrant cut aorta savagely (8)
I believe the answer is:
autocrat
'tyrant' is the definition.
(synonyms)
'cut aorta savagely' is the wordplay.
'savagely' is an anagram indicator (I've seen this in other clues).
'cut'+'aorta'='cutaorta'
'cutaorta' is an anagram of 'AUTOCRAT'.
(Other definitions for autocrat that I've seen before include "Despotic character" , "Person with unlimited power, kind of dictator" , "Actuator (anag) - dictator" , "Dictatorial type" , "Arrogant type" .)