Corded tape used for stiffening (9)
I believe the answer is:
petersham
'corded tape used for stiffening' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for petersham that I've seen before include "Material" , "Heavy corded ribbon used in belts" , "Ribbed silk ribbon" , "Stiffener" , "Corded tape used for stiffening" .)