Haven't seen the circlip, but the crank as far as i can see has nothing to do with give. The arm bar pin (where top hat gromment sits) is actually a long thin rod which fits inside the arm bar. This rod is only maybe 2mm thick. But when the plastic nut is tightened, the arm bar pin is held tightly in the arm bar, which means no give at all.
But if you loosen the plastic nut a tad, the rod has a small bit of flexibility within the arm bar- which is just enough give for certain techniques.