I think, having a "clone" button available in the "welcome" menu would be great, as it's far more often that I'd like to clone something from a remote repository than to create a new one.
Also, Xcode has the "clone" menu option.

Few people have already asked about how to clone a repository: #153, #743, so it's safe to assume, that even more people have never raised this issue even though they have the same question.

Having "clone" button available would make experience working with GitUp so much faster and intuitive.