Artificial silk — or any sort (5)
I believe the answer is:
rayon
'artificial silk' is the definition.
(I've seen this before)
'or any sort' is the wordplay.
'sort' is an anagram indicator.
'or'+'any'='orany'
'orany' anagrammed gives 'RAYON'.
(Other definitions for rayon that I've seen before include "Artificial fibre" , "Imitation silk" , "Man-made fabric" , "Semi-synthetic material" , "No ray (anag)" .)