Buck ____ is a version of the dish topped with an egg (7)

I believe the answer is:

rarebit

(Other definitions for rarebit that I've seen before include "Welsh snack" , "mouthful?" , "which the Welsh take down?" , "Arbiter (anag) -- snack" , "Cheesy snack" .)

I've seen this clue in The Sunday Times and The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.