Material from learner you incorporated in advertisement (9)
I believe the answer is:
polyester
'material' is the definition.
(polyester is a kind of material)
'learner you incorporated in advertisement' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'you' becomes 'ye' (historical version of 'you').
'incorporated in' is an insertion indicator.
'advertisement' becomes 'poster' (poster is a kind of advertisement).
'l'+'ye'='lye'
'lye' inserted within 'poster' is 'POLYESTER'.
'from' acts as a link.
(Other definitions for polyester that I've seen before include "Man-made fibre" , "Synthetic textile" , "Turn to Presley for the synthetic fabric" , "Textile material" , "This material goes out to Presley" .)