Pants regularly found in wrong material (5)
I believe the answer is:
satin
'material' is the definition.
(satin is a kind of material)
'pants regularly found in wrong' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'found in' means one lot of letters goes inside another.
'wrong' becomes 'sin' (I've seen this before**).
The alternating letters of 'pants' are 'at'.
'at' put within 'sin' is 'SATIN'.
(Other definitions for satin that I've seen before include "Smooth and silky" , "Shiny solk" , "Stain on shiny cloth" , "Stain on silky cloth" , "Smooth glossy fabric" .)