What is the error you are getting when you add this .website domain in your server?
Also, can you check the error logs to see for exact error when you add the .website domain from WHM/cPanel. # tail -f /usr/local/cpanel/logs/error_logs
in addition to what @24x7server requests do you receive a specific error when you attempt to add the domain. I was successfully able to add a .website domain to my test server running cPanel v70 this morning though I don't believe there should be an issue on v68 as well.