Crude material made better (5)
I believe the answer is:
cured
'made better' is the definition.
(I've seen this before)
'crude material' is the wordplay.
'material' indicates anagramming the letters (the letters provide the material for a new word).
'crude' with letters rearranged gives 'CURED'.
(Other definitions for cured that I've seen before include "Freed of disease" , "Of ham, smoked or salted" , "Healed - smoked" , "Made well" , "Rehabilitated" .)