Open drapes? (6,3)

I believe the answer is:

spread out

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'open drapes?' is the definition.
'spread out' can be an answer for 'open' (synonyms). I'm not certain of the 'drapes?' bit.

'open drapes?' is the wordplay.
'open' becomes 'spread' (synonyms).
'drapes?' becomes 'out' (I can't justify this - if you can you should give a lot more credence to this answer).
'spread'+'out'='SPREAD OUT'

Can you help me to learn more?

(Other definitions for spread out that I've seen before include "Move so as to cover a wider area" , "move apart" .)

I've seen this clue in The Independent.

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