Dine away from home (6)
'dine away from home' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eat out that I've seen before include "Have it in cafe" , "Dine in restaurant rather than home" , "Lunch in pub?" , "Go to restaurant for meal, don't dine at home" , "'Don't dine at home (3,3)'" .)
(Another definition for eatout that I've seen is " Encroach upon".)