Some undies can fade! (3)
I believe the answer is:
die
'fade' is the definition.
(thesaurus)
'some undies can' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'DIE' is hidden in the letters of 'undies can'.
(Other definitions for die that I've seen before include "Perish" , "One spotted" , "Depart with engraved stamp" , "Pass from physical life" , "Cease to live" .)