One who believes the worst of people (5)
I believe the answer is:
cynic
'one who believes the worst of people' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for cynic that I've seen before include "Misanthrope" , "One with a low view of human nature" , "One believing all are motivated by self-interest" , "Doubting philosopher" , "One who questions the worth of anything" .)