Omelet ingredient (3)
I believe the answer is:
egg
'omelet ingredient' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for egg that I've seen before include "Urge on the breakfast dish" , "Quiche ingredient" , "Breakfast food, perhaps" , "Good, boiled, yoke or head" , "Oval item" .)