Remove nitrous oxide, say, from impressionist (5)
I believe the answer is:
degas
This could be a double definition.
'remove nitrous oxide say' is the first definition.
'degas' can be an answer for 'remove' (degassing is a kind of removing). I'm not sure about the 'nitrous oxide say' bit.
'impressionist' is the second definition.
(I've seen this before)
'from' acts as a link.
Can you help me to learn more?
(Other definitions for degas that I've seen before include "He painted dancers" , "French artist known for his ballet scenes, d. 1917" , "Edgar ---, Fr. impressionist" , "Edgar -, Fr. artist" , "Edgar -, c. Nineteen-twenty Fr. painter" .)