A Seven of any suit orders the next player to draw two cards from the Croupier.
You can defend from a Seven if you too possess a Seven. Instead of drawing the penalty cards, play your Seven, and this will bounce off the penalty cards to the next player who will have to draw four cards instead. They can defend too, sending 6 cards to the next player and so on.
The ricocheting can continue to the point where a player might have to draw 8 cards from the Croupier at once, but this is obviously quite rare.