Subject taught by Aristotle (8)
I believe the answer is:
rhetoric
'subject taught by aristotle' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rhetoric that I've seen before include "Hot air -- rich rote (anag)" , "High-flown speech" , "Grandiose (insincere) discourse" , "Vague talk and empty promises" , "Impressive language in public speaking" .)