One unsuccessful in various roles (5)
I believe the answer is:
loser
'one unsuccessful' is the definition.
(I've seen this before)
'various roles' is the wordplay.
'various' indicates an anagram.
'roles' is an anagram of 'LOSER'.
'in' acts as a link.
(Other definitions for loser that I've seen before include "One who regularly fails" , "Opposite of winner" , "One who frequently fails (colloq.)" , "No-hoper" , "Generally inept" .)