Failure among close relatives (5)
I believe the answer is:
loser
'failure' is the definition.
(someone who has failed)
'among close relatives' is the wordplay.
'among' indicates a hidden word.
'LOSER' is hidden within 'close relatives'.
(Other definitions for loser that I've seen before include "One who regularly fails" , "One not winning" , "Failed competitor" , "One who frequently fails (colloq.)" , "Flop" .)