Not a corrupt CDPA panelist
Ah yes, I get it. It's probably the least likely of the treble to come in, so it's good to have the safety net.It means that you still back West Ham to win, but at reduced odds and with a safety net - if West Ham draw the match, the stake is refunded and the bet null and void.
In such a case, that particular wager is removed from the treble and our bet becomes a double. Of course, if the Toon contrive to win, we're stuffed regardless and the whole thing's off.