Wood outside the house had big rowan tree spreading (15)

I believe the answer is:

weatherboarding

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'wood outside the house' is the definition.
I can't judge whether this definition defines the answer.

'had big rowan tree spreading' is the wordplay.
'spreading' is an anagram indicator.
'had'+'big'+'rowan'+'tree'='hadbigrowantree'
'hadbigrowantree' with letters rearranged gives 'WEATHERBOARDING'.

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(Other definitions for weatherboarding that I've seen before include "Form of protection" , "Rainproof material" , "protection from the rain" .)

I've seen this clue in The Independent.

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