Well-wisher or fault-finder? (6)
I believe the answer is:
friend
'well-wisher' is the definition.
(thesaurus)
'fault-finder?' is the wordplay.
'fault' indicates anagramming the letters (a faulty spelling).
'finder' with letters rearranged gives 'FRIEND'.
'or' is the link.
(Other definitions for friend that I've seen before include "China" , "Close or intimate acquaintance" , "Colleague" , "Member of a religious community" , "Person with whom you have a bond of mutual affection" .)