Topless material shows class (3)
I believe the answer is:
ilk
'class' is the definition.
(thesaurus)
'topless material' is the wordplay.
'topless' means to remove the first letter.
'material' becomes 'silk' (silk is a kind of material).
'silk' with its first letter taken away is 'ILK'.
'shows' acts as a link.
(Other definitions for ilk that I've seen before include "Like" , "A kind of person" , "A certain type of person" , "Type - kind" , "Type of milksop" .)