Standing vertically? (9)

I believe the answer is:

erectness

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'standing vertically?' is the definition.
The definition and answer are not the same part of speech.

'standing vertically?' is the wordplay.
'standing' becomes 'erect' ('erect' can be similar in meaning to 'standing').
'vertically?' becomes 'ness' (I am not sure about this - if you are sure you should believe this answer much more).
'erect'+'ness'='ERECTNESS'

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I've seen this clue in The Guardian.

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