Can I sell a CodeCanyon clone on CodeCanyon?

If I develop a CodeCanyon clone and submit it for review on CodeCanyon, will it be accepted as an item?

By CodeCanyon clone I mean a platform where sellers can sign up and sell their own stuff, with a payment gateway and invoicing.

Let’s assume that its quality is up to Envato standards, of course.

It’s up to the reviewers, but I would assume as long as it is original code and up to general submission standards it has a chance of getting accepted. There are plenty of “marketplace” and “multivendor” products on Codecanyon (and Themeforest) already so I don’t think the function of your product would prevent it from being accepted.