Attractive girl worth quite a lot (6,5)

I believe the answer is:

pretty penny

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'worth quite a lot' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'attractive girl' is the wordplay.
'attractive' becomes 'pretty' (pretty can mean good-looking or attractive).
'girl' becomes 'penny' (woman's name).
'pretty'+'penny'='PRETTY PENNY'

Can you help me to learn more?

(Other definitions for pretty penny that I've seen before include "A tidy sum of money" , "Large sum of money" , "Large amount (of cost)" .)

I've seen this clue in The Mirror.

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