As of writing this, 53 Interesting Words in English That Don't Translate...
"pearl-clutching" English speaker and I never heard this. If pearl-clutching counts, there's a million more words on Urban Dictionary I'm sure
That says more about you than the list. I'm guessing you must be pretty young, because "pearl-clutching" is an older term that may be used less frequently these days, though I do still see it fairly often.
Pearl-clutching is an established idiom that's at least a good deal older than me. Honestly it's more likely that you haven't heard it because it's getting dated than because it's recent. Usually I hear it in the context of someone getting up in arms about something they consider immoral. Often the implication is that they're either being overly prudish or there's something hypocritical or judgemental about it. Someone might clutch their pearls at the idea that condoms can be bought at the drug store. Or they might do so at the idea that their children may be going to school with the children of those sort of people.
I've seen it used quite often by journalists. That would imply that it's relatively well known, since journalists are discouraged from using obscure words/phrases in titles.
> Brianna Keilar Hits Pearl-Clutching Republicans With A Very Long List Of Trump's Insults