Celebrate opera about city (9)
I believe the answer is:
singapore
'city' is the definition.
(Singapore is an example)
'celebrate opera about' is the wordplay.
'celebrate' becomes 'sing' (as in to sing someone's praises).
'about' is an anagram indicator.
'opera' is an anagram of 'apore'.
'sing'+'apore'='SINGAPORE'
(Other definitions for singapore that I've seen before include "Island nation once a British crown colony" , "Far Eastern island state" , "Asian republic" , "Small country of southeast Asia" , "Asian country, capital and mega-port" .)