Vingt-et-un (7)
I believe the answer is:
pontoon
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">vingt-et-un</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 pontoon that I've seen before include "Blackjack" , "variety of bridge" , "Card game; float" , "Bridge of boats" , "Card-game" .)