I'm after a replacement retaining clip which sits on the output shaft
of an electric motor and retains a shear pin.

The shear pin simply sits in a hole through the shaft, then around the
shaft is a semicircular depression in which the retaining clip sits.
Thus the retaining clip is a simple (split) toroid which sits in the
groove.

It's from a Vetus bow propeller and their price is £13.40 which seems
a little excessive for a trivial little spring clip.

Can anyone suggest what such a thing is called (maybe just a retaining
clip I suppose) and where I might find somewhere that I can buy one by
specifying its size?

--
Chris Green