Pessimist (5)
'pessimist' is the definition.
(I know that defeatist is a type of pessimist)
This is all the clue.
(Other definitions for defeatist that I've seen before include "With this attitude, one is resigned to failure" , "Attitude that failure is inevitable" , "One expects frustration" , "If date set (anag.)" , "Quitter" .)
'pessimist' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cynic that I've seen before include "jaded person" , "One who takes a pessimistic view of human goodness or sincerity" , "Ancient philosopher" , "One critical of the motives of others" , "Pessimistic viewer of human motives" .)