Material that hurt in revealing (9)
I believe the answer is:
towelling
'material' is the definition.
(towelling is a kind of material)
'that hurt in revealing' is the wordplay.
'that hurt' becomes 'ow' (I've seen this in other clues).
'in' indicates putting letters inside.
'revealing' becomes 'telling' (telling is a kind of revealing**).
'ow' placed inside 'telling' is 'TOWELLING'.
(Other definitions for towelling that I've seen before include "Bathrobe fabric" , "Absorbent cloth" , "Terry" .)