Cloning Ubuntu duel boot - new to cloning

So i have install a duel booted Ubuntu Server 16.04 on a separate partition on my HD intended to be used as a webserver. Windows 8 is the other OS. What I want to do is clone my Ubuntu so that if anything goes wrong, I can just reinstall from the clone, an exact copy of the original, is that how it works!?

I am new to cloning a "partition" as I have never done it before. I watched some youtube videos and it looked easy with clonezilla, but since my set-up is dual boot I am unsure if it is going to be difficult to get everything to work again. Can anyone give me pointers what I should be looking out for and initials steps?

Another question, if I am cloning to an USB external drive, does that mean I would be able to run the cloned linux from that?

Thanks!