Some vanilla, not plain (5)

I believe the answer is:

llano

'plain' is the definition.
(I've seen this before)

'some vanilla not' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'LLANO' is hidden within 'vanilla not'.

(Other definitions for llano that I've seen before include "Treeless grassy plain in South America" , "Treeless area" , "Flat area" , "Grassy plain in South?America" , "(South American) grassy plain" .)

I've seen this clue in The Telegraph.

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