Q: Can I run Hyper-V in a virtual machine running on a Hyper-V server?
A: The supported answer is no, although in a lab environment it's possible to enable the Hyper-V role within an operating system running in a Hyper-V virtual machine and create virtual machines. However, you won't actually be able to start those virtual machines, which limits their true value. If you try to enable Hyper-V from Server Manager within a virtual machine, you'll receive the error message that the following figure shows.
You therefore need to enable using PowerShell; for example:
Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All -NoRestart Install-WindowsFeature RSAT-Hyper-V-Tools -IncludeAllSubFeature
You'll then be able to create virtual machines in the virtual machine. However, if you actually try to start the virtual machine it won't be able to start. If you really need to run Hyper-V within a virtual machine, you can do so through VMware Workstation.