he had not only the 4 outs to the 3-7 straight, but 4 outs to the wheel (the 2), PLUS his Ace gave him 3 more outs to a rivered top pair, assuming you had top pair, any overpair other than AA, or a smaller pair. He has up to 11 7 outs. Even when the 4th club hits, your river lead is typically at least worth a call once he makes his straight.