Just detach your sidebar clock from the sidebar and then set it to always on top. You don't need a wall clock then.

OR...

Get another screen, and put the clock on that...

I've got an old laptop that might do the trick... given a day or so I could probably write a simple "clock-os" in assembler and boot-strap it, no doubt a great use of my time.

It still puzzles me why the clock stopped in the first place, yet I could access the date/time settings by clicking on it... even logging on/off didn't fix it - had to reboot... puzzling!