Faulty hotel in a comic opera (8)
I believe the answer is:
iolanthe
'comic opera' is the definition.
(Gilbert and Sullivan opera)
'faulty hotel in a' is the wordplay.
'faulty' is an anagram indicator.
'hotel'+'in'+'a'='hotelina'
'hotelina' is an anagram of 'IOLANTHE'.
(Other definitions for iolanthe that I've seen before include "The Peer and the Peri is its alternative title" , "G & S' alternative for "The Peer and the Peri"" , "one of 63 [OPERETTAS]" , "G&S's eponymous fairy" , "G&S operetta" .)