Whip up and turn over US snack (3,4)
I believe the answer is:
egg roll
'us snack' is the definition.
'whip up and turn over' is the wordplay.
'whip up' becomes 'egg' (to egg can mean to encourage something).
'and' says to put letters next to each other.
'turn over' becomes 'roll' ('roll' can be a synonym of 'turn over'**).
'egg'+'roll'='EGG ROLL'
(Other definitions for egg roll that I've seen before include "Fare" , "Popular Chinese starter" , "Chinese food" .)