hi
is there a script that automatically kills a non-cPanel process (processes by clients/hosting accounts) if cpu usage reaches 10% or more?

Check PRM ( Process Resource Monitor). Not sure if it meets all your requirement hence request you to go through their docs first.
Ref: http://www.webhostgear.com/85.html

You want to be careful here, often scripts and other software will use as much of your cpu that is available to get a job done. Killing off random processes could cause you much grief.