Kirk's foe whose name Kirk famously shouted in a 1982 film (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
khan
(Other definitions for khan that I've seen before include "Title taken by ancient Mongol emperors, such as Genghis" , "Title of respect in central Asia (for a descendant of Genghis?)" , "Imran --, Pakistan's PM" , "Eastern emperor" , "A Genghis successor?" .)