Material used by celebrities at interviews (5)
I believe the answer is:
satin
'material' is the definition.
(satin is a kind of material)
'used by celebrities at interviews' is the wordplay.
'used by' says the answer is hidden in the clue.
'SATIN' is hidden in the letters of 'celebrities at interviews'.
(Other definitions for satin that I've seen before include "Stain found in cloth" , "Rich cloth" , "Silky material" , "Lustrous fabric" , "covered with?" .)