Hi Lesley,
You can state this in your description and you can also create a house rule such as "Guests are expected to leave the listing in the same condition that they found it in".
Although you have not established a cleaning fee, you can still claim extra costs from the guests through the Resolution Center (https://www.airbnb.com/help/article/264/what-do-i-do-if-my-guest-breaks-something-in-my-place). If the guest does not accept your payment request, or does not respond in 72 hours, you can claim it from the Hosta Guarantee Program from Airbnb. In that case you must have an invoice from an established cleaning company.
I hope this helps.