City celebrate an opening (9)
I believe the answer is:
singapore
'city' is the definition.
(Singapore is an example)
'celebrate an opening' is the wordplay.
'celebrate' becomes 'sing' (I've seen this before).
'an' becomes 'a'.
'opening' becomes 'pore' (pore is a kind of opening).
'sing'+'a'+'pore'='SINGAPORE'
(Other definitions for singapore that I've seen before include "Site of Raffles Hotel" , "Foreign capital" , "Eastern city-state" , "SE Asia island state" , "Asian republic" .)