Whip up and turn over US snack (3,4)
I believe the answer is:
Here is my best explanation:
'us snack' is the definition.
'whip up and turn over' is the subsidiary indication.
'whip up' becomes 'egg' (to egg can mean to encourage something).
'and' means one lot of letters go next to another.
'turn over' becomes 'roll' ('roll' can be a synonym of 'turn over').
(Another definition for egg roll that I've seen is "Popular Chinese starter".)