Only worked with new material (5)
I believe the answer is:
'material' is the definition.
(nylon is a kind of material)
'only worked with new' is the wordplay.
'worked with' is an anagram indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'only' is an anagram of 'nylo'.
(Other definitions for nylon that I've seen before include "Man-made material" , "may be damaged by running" , "Artific ial (stocking) material" , "Polyamide" , "Synthetic cloth" .)