Exhibiting a supercilious and contemptuous disdain (6)
I believe the answer is:
sniffy
If this is the answer, I'm afraid I cannot explain it.
Can you help me to learn more?
(Other definitions for sniffy that I've seen before include "Scornful, contemptuous" , "Supercilious; snobby" , "Disdainful" .)