Work on furnishings before magistrate takes case (9)
I believe the answer is:
upholster
'work on furnishings before' is the definition.
I can't judge whether this definition defines the answer.
'magistrate takes case' is the wordplay.
'magistrate takes' becomes 'up' (I am not sure about this - if you are sure you should believe this answer much more).
'case' becomes 'holster' (I've seen this before).
'up'+'holster'='UPHOLSTER'
Can you help me to learn more?
(Other definitions for upholster that I've seen before include "Furnish with padding" , "Cover furniture" , "Provide furnishings" , "something to do with furniture" , "restore the throne?" .)