Combat sport (6)
I believe the answer is:
karate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">combat sport</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that karate is a type of martial arts)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for karate that I've seen before include "Japanese martial art" , "SPORT/GAME" , "method of fighting" , "Martial art (with chopping?)" , "A Jap. martial art" .)