Insect necessarily airborne? (3)
I believe the answer is:
fly
'insect' is the definition.
(fly is a kind of insect)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for fly that I've seen before include "Run away; smart (colloq.)" , "Cunning; insect" , "One invited into parlour" , "knowing about > trap" , "Move quickly; knowing" .)