Crossword Genius

One old ruin greatly admired (4)

Ross

I believe the answer is:

idol

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

'one old ruin greatly admired' is the definition.
I can't tell whether this defines the answer.

'one old ruin' is the wordplay.
'one' becomes 'i' (Roman numeral).
'ruin' indicates anagramming the letters.
'old' anagrammed gives 'dol'.
'i'+'dol'='IDOL'

Can you help me to learn more?

(Other definitions for idol that I've seen before include "Superstar; graven image" , "'Worshipped object, admired person (4)'" , "One much admired" , "Object of reverence" , "A graven image or object of adoration" .)

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