Useless; conceited (4)
I believe the answer is:
vain
I believe this is a double definition.
'useless' is the first definition.
(I've seen this before)
'conceited' is the second definition.
(synonyms)
(Other definitions for vain that I've seen before include "Useless; conceited" , "Forever looking in the mirror" , "Conceited - futile" , "Stuck-up? It's hopeless" , "It's no good" .)