A martial art (3,4,2)
I believe the answer is:
tae kwon do
'a martial art' is the definition.
(tae kwon do is a kind of martial art)
This is the entire clue.
(Other definitions for tae kwon do that I've seen before include "Koreans fighting" , "combat" , "sport" , "Martial activity" , "Modern Korean martial art" .)