What snobs put on (4)
I believe the answer is:
airs
'what snobs put on' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for airs that I've seen before include "Arrogance" , "Tunes and posturings" , "Ventilates, say grievances" , "Haughty affectation" , "affectation of superiority" .)