The most common and most likely answer to this crossword clue is the 9 letter word SWORDSMAN
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More clues leading to the result SWORDSMAN
Buddy explains!

The straight part
We know that "he is sent to fight" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case he is sent to fight = swordsman.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SWORDSMAN mean?
SWORDSMAN noun- A person skilled at using swords in sport or combat; a fencer.
- A person who fights with a sword.
- A man who is a skillful or enthusiastic practitioner of sexual intercourse.