A change of attire for number in opera (7)
I believe the answer is:
arietta
'number in opera' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'a change of attire' is the wordplay.
'change of' indicates an anagram (the letter order is changed).
'attire' anagrammed gives 'rietta'.
'a'+'rietta'='ARIETTA'
'for' is the link.
Can you help me to learn more?
(Other definitions for arietta that I've seen before include "Little song" , "Little aria" , "number from opera" , "Short operatic number" , "Short operatic air" .)