Ivan turned out to be useless (4)
I believe the answer is:
vain
'useless' is the definition.
(I've seen this before)
'ivan turned out' is the wordplay.
'turned out' indicates an anagram (turn out can mean to organise).
'ivan' is an anagram of 'VAIN'.
'to be' is the link.
(Other definitions for vain that I've seen before include "Conceited, self-important" , "Worthless" , "Useless; conceited" , "Swollen-headed" , "Concieted or pointless" .)