Simpleton's school? (4)

I believe the answer is:

eton

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

'school?' is the definition.
(famous UK public school)

'simpleton's' is the wordplay.
'ETON' is hidden within the letters.
But, I am not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for eton that I've seen before include "Town on the Thames noted for its school" , "Easy to understand" , "Posh English school of note" , "British public school of note" , "Leading English public school" .)

I've seen this clue in the Evening Standard.

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