Deliberately overlook (4)
(Other definitions for snub that I've seen before include "Cold-shoulder" , "Refuse to acknowledge" , "Slight - short and blunt - humiliation" , "unusually short" , "Rude put-down; blunt (nose)" .)
'deliberately overlook' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ignore that I've seen before include "Intentionally disregard" , "Turn a blind eye to" , "Pay no attention to, disdain" , "Discount" , "set aside" .)