I say, and with God's help: You only need to pay zakat on (5000), which is the amount exceeding the debt; as for the remaining amount, it is tied up with the debt you owe. You must subtract the amount of this debt from the money you have. If the surplus money exceeds the threshold for zakat, you only owe zakat on the surplus; otherwise, you do not owe any zakat. And God knows best.