Certain to fail (8)
I believe the answer is:
hopeless
'certain to fail' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hopeless that I've seen before include "Incompetent" , "Despairing or futile" , "Feeling despair; very bad" , "Vain" , "Unachievable" .)