Which preposition to use with clinchers

of Occurrences 1%

You don't imagine that she knows of any larger force anywhere in the neighbourhood?" "She can't know of any, for there ain't any," was the clincher of the rustler; "or, if there is, she can't get it here in time to do Asbury and the rest any good.

on Occurrences 1%

I wished the harness had not broken, as I feared it would put a clincher on my being allowed out driving alone in future.

Which preposition to use with  clinchers