Is it possible to do a "clean" install of Lion?
Yes, it is possible. It is bootable, and will be able to do a complete clean install (with you having to format the hard disk first).

Also, if you have installed Lion already, you would be able to do a reinstall by holding ⌥ Option on bootup and selecting Recovery HD. Wait for it to load, and you will be able to see an option for reinstalling.