Bridge? It’s a card game (7)
I believe the answer is:
pontoon
This clue is a double definition.
'bridge?' is the first definition.
(pontoon bridge is a kind of bridge)
'a card game' is the second definition.
(I've seen this before)
'it's' is the link.
(Other definitions for pontoon that I've seen before include "Card game; floating support" , "variety of bridge" , "Vingt-et-un" , "Blackjack" , "Bridge of boats" .)