Ultimate in fashion, only tailored material (5)
I believe the answer is:
nylon
'material' is the definition.
(nylon is a kind of material)
'ultimate in fashion only tailored' is the wordplay.
'ultimate in' indicates one should take the final letters.
'tailored' indicates anagramming the letters (the letters are customised ).
The last letter of 'fashion' is 'n'.
'only' with letters rearranged gives 'ylon'.
'n'+'ylon'='NYLON'
(Other definitions for nylon that I've seen before include "The first synthetic fibre" , "Man-made fabric" , "Cover for leg" , "Hosiery material" , "Plastic used for stockings" .)