Royal family treasuring good times over in European city (9)

I believe the answer is:

stuttgart

I'm a little stuck... Click here to teach me more about this clue!

'european city' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for stuttgart that I've seen before include "Capital of Baden-Wurttemberg" , "City in Germany" , "City, capital of Baden-WYrttemberg" , "European city" , "Ger. city on R. Neckar" .)

I've seen this clue in The Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.