Hi, Rusty!
I didn't even know of the musician in question , and was happy enough when I worked out "Suppe", from the parsing of the clue , just to put it in the grid!
I only learned the guy's full name just now when reading your message.
( I didn't bother to look it up - I should have done, I know!)
Had I done so, I would have thought, like you did, that von Suppe was his surname?
Remember the von Trapp family? and the von Trapp family singers?
I don't think that they were ever referred to as just "The Trapps"?
But I cannot offer that with any authority.
I knew of Jocasta.......and funnily enough came across "tempura" a short time ago.
I think Barry might have referred to it on "Eggheads..
Barry is a keen fan of anything Japanese!"