Where to find replacement Clarks Skeletal right brake?
If you’re struggling to find a replacement part online, others would probably be googling the same terms and struggle too. 

What you might not appreciate about your local bike shop is that shops generally have access to the majority of cycling brands through their various suppliers, even if you don’t see that brand on their shelves. It would be pretty trivial for a good shop to order something in if they can get it. 

If they can’t find an exact replacement they might be able to show the current range and spot a compatible replacement lever. 

You could also replace the whole brake for a different model as alluded to by mattnz, or have a go at drilling out the screw if it’s otherwise junk - might be prohibitively small!