Embee, re rile - i can't see how 'regulation' comes into play. rifle(upset) minus f = rile(also, upset).
still, i don't like my explanation much either.
don't have the clue for your request.
Thanks Rambler - I'd always heard it called a Jews Harp but knew this couldn't fit - wind is too obvious for me! Sorry Trevor - clue is "Blow operating this if one doesn't have the pluck (4,4)". I think rile and rule are equally non-18 down! ("Where one's out bagging information that's convincing (6)")
Embee, i think you may be right about rile/rule (took me a while to solve 18a though,lol).
i think the term Jew's Harp has fallen victim to the PC brigade.
I've always called it that(so did the shop where i bought one). not familiar with Wind Harp.
You're right about the PC thing Trevor, I winced as I typed the word in case anyone objected. But whilst Leonard Cohen, who is Jewish, continues to sing about them I don't think we need to rewrite our dictionaries!