Cheap floor (5-4)

I believe the answer is:

knock down

I believe this clue is a double definition.

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

'floor' is the second definition.
(synonyms)

(Other definitions for knock down that I've seen before include "aim of Haye, say" , "level" , "very low in price" , "Cheap - floor" , "Easily dismantled furniture" .)

I've seen this clue in The Guardian.

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