You can't do a clean install of 10.11.1 till it is publicly released because so far there is no full installer for it.
The "cleanest" you can do now is to clean install 10.11 and then update to 10.11.1 but technically that is not a clean install.
When it is publicly released, you can then download the full installer for 10.11.1 and then do the clean install.