This material sounds swell (5)
I believe the answer is:
serge
'this material' is the definition.
(serge is a kind of material)
'sounds swell' is the wordplay.
'sounds' indicates a 'sounds like' (homophone) clue.
'swell' becomes 'surge' (I've seen this before).
'surge' sounds like 'SERGE'.
(Other definitions for serge that I've seen before include "A twill fabric" , "Twilled woollen fabric" , "Strong twilled worsted fabric" , "Frenchman" , "Twilled fabric; name" .)