Patronising (13)
I believe the answer is:
condescending
'patronising' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for condescending that I've seen before include "Snooty" , "Disdainful" , "Supercilious" , "Toffee-nosed" , "Offensively patronising" .)