There is a simple way to extract xpi file from mozilla profile, so I did it with my clipper. Here it is, 6.1 version, if anyone is interested.
Though you may want to consider that I may not be trusted as an xpi source and that maybe 6.1 was removed from ff addons for some good reason. But it works well for me, and my problem with "exception at..." error (while trying to use "Simplified clipping") was resolved by installing 6.1. And - don't break yours, if it's working