Part of introvert I called upright (8)

I believe the answer is:

vertical

'upright' is the definition.
(I know that upright can be written as vertical)

'part of introvert i called' is the wordplay.
'part of' indicates a hidden word.
'VERTICAL' is hidden in the letters of 'introvert i called'.

(Other definitions for vertical that I've seen before include "Upright, perpendicular" , "Straight up" , "Not laid down" , "Perfectly upright" , "Absolutely upright" .)

I've seen this clue in the Sydney Morning Herald.

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