Only prepared new material (5)
I believe the answer is:
nylon
'material' is the definition.
(nylon is a kind of material)
'only prepared new' is the wordplay.
'prepared' is an anagram indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'only' is an anagram of 'nylo'.
'nylo'+'n'='NYLON'
(Other definitions for nylon that I've seen before include "Tights material" , "Artificial fibre" , "A thermoplastic" , "Synthetic material used in textiles" , "Plastic used for stockings" .)