Have you seen a Perl/Moose wrapper for Tk.
Or other suggestions how to cleanly build/code a GUI with Perl!
No, there isn't. There are three (that I'm aware of) sets of bindings from Perl to Tk: Perl/Tk, Tkx, and Tcl::Tk. All are object-oriented, but none of them use Moose.
Since these are modules that you will use, not modify, I don't see the advantage of wrapping them with Moose. You can write perfectly clean code using them directly. The most important thing is to cleanly separate the UI code from the business logic (which could use Moose).