I'm basing my answer purely on the information that you've given, so don't take this as legal advice. There are a lot of other factors that could affect the situation, and more facts would be required to make that determination. That being said, exclusive use clauses are a very common provision in retail leases, and you generally cannot get out of them. Their very purpose is to provide a competitive advantage to the lessee...thereby inducing them to take space in your project. Most regional and national chains require them. Absent some exigencies that I am unaware of, your chances of getting around that clause are not great from a legal perspective.
As some others have said, though, you might just try having a conversation with the tenant. There may be different owners, now, and some restaurants are actually symbiotic with others.
Feb 4, 2011