King meeting a judge for contact sport (6)
I believe the answer is:
karate
'contact sport' is the definition.
(martial art)
'king meeting a judge' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'meeting' means one lot of letters go next to another.
'judge' becomes 'rate' (rating is a kind of judging).
'k'+'a'+'rate'='KARATE'
'for' is the link.
(Other definitions for karate that I've seen before include "Jap. combat; sort of chop" , "A Jap. martial art" , "Japanese art of unarmed combat" , "method of fighting" , "SPORT/GAME" .)