Wind, Eastern, expressing a sort of air (4)
I believe the answer is:
glee
'sort of air' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'wind eastern expressing a' is the wordplay.
'wind' becomes 'gale' (gale is a kind of wind).
'eastern' becomes 'e'.
'expressing' indicates named letters should be taken away.
'gale'+'e'='galee'
'galee' with 'a' taken out is 'GLEE'.
Can you help me to learn more?
(Other definitions for glee that I've seen before include "Great delight; part song" , "Mirth - part-song" , "Great merriment" , "Great pleasure" , "Unrestrained joy" .)