It's found in Paris - cool in Athens (9)
I believe the answer is:
acropolis
'athens' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'it's found in paris cool' is the wordplay.
'it's found in' indicates anagramming the letters.
'paris'+'cool'='pariscool'
'pariscool' with letters rearranged gives 'ACROPOLIS'.
'in' is the link.
Can you help me to learn more?
(Other definitions for acropolis that I've seen before include "Citadel of ancient Greece" , "place of high security" , "Upper fortified part of Greek city - Athens's is famous" , "Imposing building" , "Athens landmark" .)