Insect that won't necessarily take to the air? (6)
I believe the answer is:
mayfly
'insect that won't' is the definition.
'mayfly' can be an answer for 'insect' (mayfly is a kind of insect). I am not certain of the remainder of the definition.
'necessarily take to the air?' is the wordplay.
'necessarily' becomes 'may' (I can't justify this - if you can you should give a lot more credence to this answer).
'take to the air?' becomes 'fly'.
'may'+'fly'='MAYFLY'
Can you help me to learn more?
(Other definitions for mayfly that I've seen before include "Ephemeral insect" , "Short-lived spring insect" , "Short-lived insect with delicate wings" .)