What a Clover sale writes
One invoice per order, in draft, in your currency.
Each Clover sale rung at the register becomes one draft invoice in Xero: the customer matched or created as a contact where Clover recorded one, one line per item at the price taken, and the register’s currency. It lands as a draft so you approve it in Xero the way you approve anything else.
Clover tells us the moment something sells, so the draft invoice is in Xero a second or so later. Cancel the order before you approve the invoice and the draft is removed. Anything you have already approved is yours to credit in Xero.