Philosopher with authority becomes factory designer (10)
I believe the answer is:
millwright
'factory designer' is the definition.
(someone who designs mills)
'philosopher with authority' is the wordplay.
'philosopher' becomes 'mill' (I've seen this in other clues).
'with' becomes 'w' (abbreviation).
'authority' becomes 'right' (I've seen this before).
'mill'+'w'+'right'='MILLWRIGHT'
'becomes' acts as a link.
(Other definitions for millwright that I've seen before include "Maker of machinery" , "builder of Tulliver's place" .)