Money that, by your own admission, you proved to have paid (8,3)

I believe the answer is:

entrance fee

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

'money that by your own admission you proved to have paid' is the definition.
The answer and definition can be both related to property as well as being singular nouns.
Maybe they are linked in a way I don't understand?

This is all the clue.

Can you help me to learn more?

(Other definitions for entrance fee that I've seen before include "Admission charge" , "Getting in charge" .)

I've seen this clue in the Evening Standard.

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.