@mukul I don’t know that it’s possible to define a name server within a name server. At your registrar (name.com), you have set Netlify to be the name server for your domain. You cannot then tell Netlify name servers to use someone else’s name servers.
One way to approach this would be to change the DNS entries with Name.com to point to the DNS for your WordPress install (as this seems to be what you want to do). If you just want to run WordPress on a separate server without a Netlify site at a different subdomain, this is the most straightforward.
If you want to run both a WordPress site (on a separate server) and a Netlify site off of this custom domain, then you might think about deleting the NS records for your WordPress site from the Netlify DNS and use redirects to sort out which traffic goes where.