Furniture has notice inside square base (4,6,3)

I believe the answer is:

four-poster bed

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'square base' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'furniture has notice' is the wordplay.
'furniture' becomes 'fourposter' (four-poster is a kind of furniture).
'has notice' becomes 'bed' (I am not sure about this - if you are sure you should believe this answer much more).
'fourposter'+'bed'='FOUR POSTER BED'

'inside' is the link.

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I've seen this clue in The Times.

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