Nice friends succeeded? Wrong! (5)
I believe the answer is:
amiss
'wrong' is the definition.
(I know that wrong can be written as amiss)
'nice friends succeeded?' is the wordplay.
'nice friends' becomes 'amis' ('friends' in French eg in Nice).
'succeeded?' becomes 's' (genealogical abbreviation).
'amis'+'s'='AMISS'
(Other definitions for amiss that I've seen before include "Not functioning properly" , "Wrorg" , "Taking wrong turn" , "Mistakenly" , "Wrong - awry" .)