This is a physical-to-virtual ("P2V") transfer. Here's how I've done it in the past (from memory - your mileage may vary):
1. Assuming you have your Clonezilla image of the physical machine on an external drive, plug that drive into the Proxmox VM host.
2. Upload a Clonezilla ISO image to Proxmox (in the images section of Local Storage) so that you can boot a VM from it.
3. Create a new Proxmox KVM guest and select the Proxmox ISO for its CD drive. Create a virtual HD for the VM that's as least as big as the machine you cloned - maybe 1G bigger, just in case.
4. Make the drive you've just plugged in available to the Proxmox VM with "qm set <id> -<drivetype> /dev/<device>", where <id> is the VM ID number you see in the Proxmox UI, <drivetype> is ide1, virtio1 or whatever you chose in step 3, and <device> is the device of the disk with the Clonezilla image on it (eg sdb1).
5. Boot the VM with Clonezilla and choose manual mounting of disk to /home/partimag - then restore the machine to the virtual HD (use fdisk -l for the device name you need to specify for Clonezilla)
6. Shut down the VM once Clonezilla has finished, and remove the ISO from the VM's CD drive.
7. Boot the VM and your physical machine should now be running in it.
