What makes round brown circle in sampler (7)

I believe the answer is:

toaster

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'what makes round brown' is the definition.
I can't tell whether this definition defines the answer.

'circle in sampler' is the wordplay.
'circle' becomes 'O' (O is a circle).
'in' is an insertion indicator.
'sampler' becomes 'taster' (I've seen this before).
'o' going into 'taster' is 'TOASTER'.

Can you help me to learn more?

(Other definitions for toaster that I've seen before include "Kitchen device" , "One raising glass" , "wedding present?" , "Health-promoting" , "Best man" .)

I've seen this clue in The Times.

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