Equestrian game (4)
I believe the answer is:
polo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">equestrian game</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for polo that I've seen before include "car?" , "explorer of the thirteenth century" , "In which horsemen attack and defend" , "It's played in water and on horseback" , "Venetian 19 to Asia, servant to Kublai Khan" .)