Ballet is performed in fortress (8)
I believe the answer is:
bastille
'fortress' is the definition.
(I've seen this before)
'ballet is performed' is the wordplay.
'performed' is an anagram indicator.
'ballet'+'is'='balletis'
'balletis' is an anagram of 'BASTILLE'.
'in' acts as a link.
(Other definitions for bastille that I've seen before include "Fortress in Paris" , "Parisian fortress" , "Fortress stormed on July 14, 1789" , "Old Parisian prison" , "Old fortress" .)