It airily responds to thermal movement (6)
I believe the answer is:
glider
'it airily responds to thermal' is the definition.
The definition suggests a singular noun which matches the answer.
'movement' is the wordplay.
I cannot really see how this works, but
'movement' could be 'glide' (glide is a kind of movement) and 'glide' is found in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for glider that I've seen before include "craft without power" , "A sort of possum" , "Sailplane" , "Powerless aircraft" , "quiet flier" .)