Brute best kept out of the day centre (5)

I believe the answer is:

beast

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'brute' is the definition.
(I know that brute can be written as beast)

'best kept out of the day centre' is the wordplay.
'kept' indicates putting letters inside.
'out of the day centre' becomes 'a' (I can't explain this - if you can you should believe this answer much more).
'best' placed around 'a' is 'BEAST'.

Can you help me to learn more?

(Other definitions for beast that I've seen before include "Monstrous person" , "Wild animal" , "rotter" , "Inhuman person" , "Savage" .)

I've seen this clue in the Evening Standard.

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