An air of finality (4,4)
I believe the answer is:
swan song
'finality' is the definition.
(thesaurus)
'an air' is the wordplay.
I cannot quite see how this works, but
'an' could be 'a' and 'a' is present in the answer.
'air' could be 'song' (I've seen this in another clue) and 'song' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for swan song that I've seen before include "Final performance, as the air of an aquatic bird" , "Final performance, last hurrah" , "Last act or work, as of noble bird" , "Musician's final appearance" , "Bird music for last act before death or retirement" .)