The FAM calls it a Pin Lock (PN 359380). Shown on Section 5, Sheet 2.00.
I'm not sure a C-clip would work, but it might. I don't recall exactly what the end of the shaft looks like, but the "Pin Lock" is weird. It's soft metal and bends pretty easily.
The end of the shaft has a square cut groove cut in it just like what is called for when using a c-clip. All you need to figure out is the correct thickness and diameter of the groove to select the right c-clip.
