This is a (very) rough outline to get you up and running. You will need to go through the following steps:
In ClearOS, dnsmasq (DNS and DHCP server) binds to all IP's. This includes the libvirt virbr0 interface and it stops libvirt from starting. This behaviour needs to be changed. Create a file /etc/dnsmasq.d/libvirt and in it put:
If there are any other files in this folder with “bind-interfaces” in them, the “bind-interfaces” line should be removed or changed to “bind-dynamic”. Then try restarting dnsmasq and libvirt with:
systemctl restart dnsmasq libvirtd
If that does not work, reboot.
When you download an iso into Kimchi, you won't have permission to run it. Either change the file ownership to qemu:qemu or make it world readable:
chown qemu:qemu /var/lib/kimchi/isos/*
chmod 0644 /var/lib/kimchi/isos/*
If your server has only one NIC, you can still use Kimchi. In the Virtialization > Network tab, create a Macvtap interface and attach it to your ClearOS interface. Then use the Macvtap interface in your guests. Your guests will then pull a DHCP IP address from your DHCP server. The only limitation is that your host and guest machines cannot communicate directly, so, for example, your ClearOS host will not be able to ping any of its VM guests.