Bedaub (5)
I believe the answer is:
smear
'bedaub' is the definition.
(synonyms)
This is all the clue.
(Other definitions for smear that I've seen before include "allegation" , "Medical examiner may take this" , "sample on slide" , "Slanderous denigration of character" , "Bedaub with oily stuff - defame" .)