Is there a way to ensure new clients can't schedule with a clinician who has a full caseload?

Is there a way to handle this better? 

We want the client portal to be open to current clients for scheduling, but sometimes a clinician will have availability showing because clients have canceled or have schedules that change week to week, and it shows as available for new clients. We would love to prevent new clients from being able to schedule with clinicians who are not accepting new clients while still allowing new clients to access the client portal, so that they can schedule with clinicians who are actually accpting new clients. Is there a way to design this in our permissions?