Material glut went unrestricted (6)
I believe the answer is:
sateen
'material' is the definition.
(I know that sateen is a type of material)
'glut went unrestricted' is the wordplay.
'glut' becomes 'sate' (I've seen this in another clue).
'unrestricted' says to take the centre (remove the outside letters which restrict the rest).
The middle of 'went' is 'en'.
'sate'+'en'='SATEEN'
(Other definitions for sateen that I've seen before include "Glossy material" , "Shiny cloth found in senate" , "Shiny cloth used for furnishings" , "Glossy cotton fabric" , "Closely woven cotton fabric resembling satin" .)