Twilled suit fabric (5)
I believe the answer is:
serge
'twilled suit fabric' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for serge that I've seen before include "Frenchman" , "Twilled woollen fabric" , "A twill fabric" , "Strong twilled worsted fabric" , "Twilled fabric; name" .)