Film company boss joining impresario on vacation (6)
I believe the answer is:
studio
'film company' is the definition.
(as in a film studio)
'boss joining impresario on vacation' is the wordplay.
'boss' becomes 'stud' (both can mean a metal decoration).
'joining' says to put letters next to each other.
'on vacation' suggests removing the centre.
'impresario' with its middle taken out is 'io'.
'stud'+'io'='STUDIO'
(Other definitions for studio that I've seen before include "Artist's workshop" , "Recording or painting workshop" , "Small apartment" , "Film producer" , "Elstree area" .)