Try air for its unusualness (6)
I believe the answer is:
rarity
'unusualness' is the definition.
(thesaurus)
'try air for its' is the wordplay.
'try air' can be anagrammed to 'RARITY'.
But, I'm not clear how the anagram is indicated.
Can you help me to learn more?
(Other definitions for rarity that I've seen before include "Uncommonness" , "'Something unusual, perhaps collectable (6)'" , "could be something of value" , "It occurs infrequently" , "You don't see it very often" .)