Modelled fashionable material (5)
I believe the answer is:
satin
'material' is the definition.
(I know that satin is a type of material)
'modelled fashionable' is the wordplay.
'modelled' becomes 'sat' ('sit' can be a synonym of 'model').
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'sat'+'in'='SATIN'
(Other definitions for satin that I've seen before include "Stain on silky cloth" , "Stain found in cloth" , "Rich cloth" , "Smooth glossy fabric" , "Stain on shiny cloth" .)