Japanese military governor (6)
I believe the answer is:
shogun
'japanese military governor' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for shogun that I've seen before include "Japanese head" , "Foreign C-in-C" , "Japanese military dictator" , "Hereditary commander-in-chief in feudal Japan" , "Hereditary military dictator of Japan until 1868" .)