Part of screed is malicious, dreary (6)
I believe the answer is:
dismal
'dreary' is the definition.
(I've seen this before)
'part of screed is malicious' is the wordplay.
'part of' says the answer is hidden in the clue.
'DISMAL' can be found hidden inside 'screed is malicious'.
(Other definitions for dismal that I've seen before include "Lugubrious" , "Dull and dreary" , "dark" , "Pessimist -- is my jam mild? (anag)" , "Dull; doleful" .)