Family joined by good man (4)
I believe the answer is:
king
'man' is the definition.
(man can mean a chess piece)
'family joined by good' is the wordplay.
'family' becomes 'kin' (synonyms).
'joined by' is a charade indicator (letters next to each other).
'good' becomes 'g' (abbreviation).
'kin'+'g'='KING'
(Other definitions for king that I've seen before include "and 21 Across: Shakespeare play" , "See 23 Down" , "initially unable to move" , "Martin Luther -" , "Male monarch" .)