Drone getting to grips with reasonably hot air (5)
I believe the answer is:
hokum
'hot air' is the definition.
(thesaurus)
'drone getting to grips with reasonably' is the wordplay.
'drone' becomes 'hum' (I've seen this in another clue).
'getting to grips with' means one lot of letters goes inside another.
'reasonably' becomes 'ok' (I can't explain this - if you can you should give a lot more credence to this answer).
'hum' enclosing 'ok' is 'HOKUM'.
Can you help me to learn more?
(Other definitions for hokum that I've seen before include "gammon" , "Be extremely good (at activity)" , "Sentimental stuff in play or film, nonsense" , "Hogwash" , "Nonsense (colloq.)" .)