Actors join the French piece (6)
I believe the answer is:
castle
'piece' is the definition.
(castle is a kind of piece)
'actors join the french' is the wordplay.
'actors' becomes 'cast' (I've seen this before).
'join' means one lot of letters go next to another.
'the french' becomes 'le'.
'cast'+'le'='CASTLE'
(Other definitions for castle that I've seen before include "Move king to safety - stronghold" , "splendid house" , "E.g. Harlech, Beaumaris, Windsor" , "Chess piece and fortified building" , "''An Englishman's home is his . . .''" .)