Ready for Janacek? Knockout sequence of notes at end of Sinfonietta (6)

I believe the answer is:

koruna

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

'ready' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.

I can't explain the remainder of the clue.

Can you help me to learn more?

I've seen this clue in The Times and The Sunday Times.

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.