Carpets made up beforehand (7)

I believe the answer is:

precast

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'beforehand' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?

'carpets made up' is the wordplay.
'made up' indicates an anagram.
'carpets' with letters rearranged gives 'PRECAST'.

Can you help me to learn more?

(Other definitions for precast that I've seen before include "(Of concrete) formed before positioning" , "made earlier" .)

I've seen this clue in The Globe and Mail.

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