Blemish beautiful cereal boxes (5)

I believe the answer is:

ulcer

I'm a little stuck... Click here to teach me more about this clue!

'blemish beautiful cereal boxes' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.

'blemish beautiful cereal boxes' is the wordplay.
'boxes' indicates a hidden word (to box can mean to contain).
'ULCER' is hidden in the letters of 'blemish beautiful cereal'.

Can you help me to learn more?

(Other definitions for ulcer that I've seen before include "Stomach or mouth sore" , "Cruel form of stomach trouble?" , "Cruel kind of bodily sore" , "Continuing source of pain" , "Sore point" .)

I've seen this clue in The Independent.

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.

Connecting...