Piece of furniture that's chosen by PM (7)
I believe the answer is:
cabinet
'piece of furniture' is the definition.
(cabinet is a kind of piece of furniture)
'chosen by pm' is the wordplay.
I cannot really understand how this works, but
'chosen' could be 'in' ('you're in!') and 'in' is found in the answer.
This explanation may well be incorrect...
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for cabinet that I've seen before include "Peel once topped this" , "Display cupboard - senior ministers" , "It may be shelved" , "Piece of furniture with doors, shelves and drawers" , "Furniture item or collective government ministers" .)