How to use CWP only for subdomain from other hosting account

I installed CWP and I would like to point subdomain from my other hosting via A record to CWP. I would like tu use subdomain crm.mydomain.com in CWP but I'm hosting that domain on other hostig account and I want to use CWP only for one subdomain

How to set this?

Simply create subdomain on that main hosting hosting and as IP (A record) set your cwp's ip address, then create account on cwp and as domain enter subdomain you've created on your main hosting.
If you have CPanel use one of zone editor modules to create subdomain that can be manually re/directed to different ip address.
It is important that the domain/subdomain is re/directed to cwp's ip address, then you can do what ever you want on cwp with it.

That should work.