Thank you!
A bit strange that this command is not present in this list:
> pve:/nodes/{MY_NODE}/qemu/{MY_VMID}> help
> help [path] [--verbose]
> cd [path]
> ls [path]
>
> delete /nodes/{node}/qemu/{vmid} [OPTIONS]
> get /nodes/{node}/qemu/{vmid}/config
> set /nodes/{node}/qemu/{vmid}/config [OPTIONS]
> create /nodes/{node}/qemu/{vmid}/migrate -target <string> [OPTIONS]
> create /nodes/{node}/qemu/{vmid}/monitor -command <string> [OPTIONS]
> set /nodes/{node}/qemu/{vmid}/resize -disk <string> -size <string> [OPTIONS]
> get /nodes/{node}/qemu/{vmid}/rrd -ds <string> -timeframe <string> [OPTIONS]
> get /nodes/{node}/qemu/{vmid}/rrddata -timeframe <string> [OPTIONS]
> create /nodes/{node}/qemu/{vmid}/snapshot -snapname <string> [OPTIONS]
> set /nodes/{node}/qemu/{vmid}/unlink -idlist <string> [OPTIONS]
> create /nodes/{node}/qemu/{vmid}/vncproxy
But:
> pve:/nodes/{MY_NODE}/qemu/{MY_VMID}> help clone
> help [path] [--verbose]
> cd [path]
> ls [path]
>
> create /nodes/{node}/qemu/{vmid}/clone -newid <integer> [OPTIONS]
Bug ?