Hi,
Have you configured both data and managment port? If you configured data port then radius request will go to data port.
NOTE: The Data Port IP Address must not be in the same subnet as the Management Port IP Address.
Were you able to ping the data port IP from switch? Have you provided correct radius server IP and shared key details in switch, make sure it matches with clearpass key.
Make sure port 1812 is opened if their is any firewall in your network.
After checking above details, if you still have issue, try restart the services.
Regards,
Pavan