Unlike assemblies with Spirolox spiral retaining rings or Circlips snap rings, components held in place by hoop-style retaining rings may have a corner break.

Our engineers were faced with a problem when asked by one of our leading automotive electric motor OEM's to supply a 33mm external retaining ring capable of withstanding rotational speeds in excess of ...

The clip you've got in your photo is called a "circlip". I agree with above, you're definitely going to be better served by a replacement fan, as parts like that aren't usually standardized.