P G Wodehouse joke: explanation?

I’m reading Spring Fever, a P G Wodehouse novel from about 1947, and they are constantly referring to “am-parce.” We assume it’s some sort of joke-reference, but we don’t get it. It’s used in the sense of a situation – perhaps a pun on impasse?

Anyone got any clue?

IIRC, the context was “The only way to solve the am-parce…”, which I just took to be a phonetic rendering into English of impasse.

Probably. “Impasse,” in French, would be pronounced, roughly, “am-pahse.” The “ah” might well be spelled “ar” in a non-rhotic dialect like English. (Hence also, for example, the American “um” spelled “erm” in British dialect.)