You can't make one without breaking eggs (8)
I believe the answer is:
omelette
'you can't make one without breaking eggs' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for omelette that I've seen before include "Beaten-egg dish" , "Dish of cooked beaten eggs" , "Having panned meal" , "You can't make one without breaking eggs" , "Simple egg dish" .)