Military ruler's weapon missing target ultimately (6)

I believe the answer is:

shogun

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'military ruler's' is the definition.

I can't explain the rest of the clue.

(Other definitions for shogun that I've seen before include "Hereditary military governor in Japan" , "Hereditary commander of feudal Japanese army" , "Hereditary commander-in-chief in feudal Japan" , "Dominant Japanese" , "Former military governor of Japan" .)

I've seen this clue in The Telegraph.

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