Song involving duo — it excited parts of concert-halls (9)
I believe the answer is:
auditoria
'parts of concert-halls' is the definition.
(plural of 'auditorium')
'song involving duo it excited' is the wordplay.
'song' becomes 'aria' (aria is a kind of song).
'involving' means one lot of letters goes inside another.
'excited' is an anagram indicator.
'duo'+'it'='duoit'
'duoit' anagrammed gives 'udito'.
'aria' going around 'udito' is 'AUDITORIA'.
(Other definitions for auditoria that I've seen before include "music halls" , "Where concertgoers sit" , "Spaces for audiences" , "Theatre areas for spectators or listeners" , "Theatres, concert halls" .)