Military ruler’s command to soldiers about bad error in field (6)
I believe the answer is:
shogun
'military ruler's' is the definition.
'shogun' can be an answer for 'ruler's' (shogun is a kind of ruler). I am unsure of the 'military' bit.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for shogun that I've seen before include "So hung about with old Japanese army commander" , "Hereditary Japanese military governor" , "Leader in feudal Japan" , "Hereditary military dictator of Japan until 1868" , "Old Japanese hereditary army commander" .)