Fictional doctor and wife visiting family member (6)
I believe the answer is:
watson
'fictional doctor' is the definition.
(Doctor Watson, friend of Sherlock Holmes)
'wife visiting family member' is the wordplay.
'wife' becomes 'w' (abbreviation).
'visiting' becomes 'at'.
'family member' becomes 'son' (I've seen this in other clues).
'w'+'at'+'son'='WATSON'
'and' is the link.
(Other definitions for watson that I've seen before include "Holmes' assistant" , "Doctor colleague of Sherlock Holmes" , "Sherlock Holmes's doctor companion" , "Holmes' associate" , "I helped detective" .)