Fighter is harmful when ignoring the odds: right then left from boxer (7)
I believe the answer is:
samurai
'fighter' is the definition.
(samurai is a type of warrior or fighter)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for samurai that I've seen before include "Japanese militarist" , "Seven -, film directed by Kurosawa" , "Sudoku variant" , "Member of military class" , "Traditional Japanese warrior" .)