A long number of answers, including right one (4)
I believe the answer is:
aria
'a long number' is the definition.
(a long musical number in an opera)
'answers including right one' is the wordplay.
'answers' becomes 'ai' (I can't justify this - if you can you should believe this answer much more).
'including' is an insertion indicator.
'right' becomes 'r' (common abbreviation).
'one' becomes 'a'.
'ai' enclosing 'r' is 'ari'.
'ari'+'a'='ARIA'
'of' is the link.
(Other definitions for aria that I've seen before include "Song such as "Your Tiny Hand is Frozen"" , "Song, one from 'West Side Story' needing no introduction" , "Operatic number" , "Elaborate accompanied song for solo voice" , "Operatic solo, duet, etc" .)