Futile; conceited (4)
I believe the answer is:
vain
I believe this clue is a double definition.
'futile' is the first definition.
(I know that futile can be written as vain)
'conceited' is the second definition.
(I know that conceited can be written as vain)
(Other definitions for vain that I've seen before include "thoughtless" , "Conceited, arrogant" , "Conceited, self-important" , "Concieted or pointless" , "Conceited and ineffectual" .)