Respected heads of army units and air force (6)
I believe the answer is:
august
'respected' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I can't see?
'heads of army units and air force' is the wordplay.
'heads of' suggests taking the first letters.
'and' says to put letters next to each other.
'air force' becomes 'gust' (I can't justify this - if you can you should believe this answer much more).
The initial letters of 'army units' is 'au'.
'au'+'gust'='AUGUST'
Can you help me to learn more?
(Other definitions for august that I've seen before include "comic entertainer for children" , ". . . . . . is a Wicked Month (Edna O'Brien)" , "Respected and impressive in the month" , "Inspiring respect; month" , "Dignified - month" .)