Broadcast only new material (5)
I believe the answer is:
nylon
'material' is the definition.
(nylon is a kind of material)
'broadcast only new' is the wordplay.
'broadcast' indicates an anagram.
'new' becomes 'n'.
'only' anagrammed gives 'nylo'.
'nylo'+'n'='NYLON'
(Other definitions for nylon that I've seen before include "Synthetic material used in textiles" , "Artificial yarn/fabric" , "Artificial cloth" , "Artific ial (stocking) material" , "Polyamide" .)