Bastion of cool Paris fashion (9)
I believe the answer is:
acropolis
'bastion' is the definition.
(acropolis is a kind of bastion)
'cool paris fashion' is the wordplay.
'fashion' indicates an anagram.
'cool'+'paris'='coolparis'
'coolparis' anagrammed gives 'ACROPOLIS'.
'of' acts as a link.
(Other definitions for acropolis that I've seen before include "Upper fortified part of Greek city - Athens's is famous" , "place of high security" , "Athenian landmark" , "Large old building" , "classical site" .)