Height of a factory? (3)

I believe the answer is:

tor

'height' is the definition.
(I've seen this before)

'of a factory?' is the wordplay.
'of' says the answer is hidden in the clue.
'TOR' is hidden within 'factory'.

(Other definitions for tor that I've seen before include "Feature of Dartmoor" , "Fermenting agent" , "feature of Glastonbury" , "Rot on a hill in Cornwall" , "Rocky prominence" .)

I've seen this clue in the Evening Standard.

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