The easiest way would be to use Meraki WiFi and Systems Manager and spend 15 seconds, yes, SECONDS deploying certs to all of your devices, utilising the built in PKI and RADIUS in Meraki Dashboard
But, as you're not doing that, so....
1. Create a new Setting (Systems Manager > Settings > Add profile)
2. Give is a name
3. Add a certificate payload: You'll have to reach out to ClearPaass to work out what type, either dynamic or static
4. Add a wifi payload to the same setting, and configure the various 802.1x options under Security > WPA2 Enterprise > Protocols / Authentication / Trust
5. Under Authentication > Identity Certificate, choose the SCEP / Cert payload you created earlier