CRUST is a playable word

crust Scrabble® Dictionary

verb
crusted, crusting, crusts
to form a crust (a hardened outer surface)
16 Playable Words can be made from "CRUST"
   2-Letter Words (2 found)
   3-Letter Words (5 found)
   4-Letter Words (7 found)
   5-Letter Words (2 found)