Kitchen cabinet (4)
(Other definitions for unit that I've seen before include "Subdivision of a military group" , "Entity making up part of a whole" , "squad" , "army group" , "Single whole as part of a larger whole" .)
'kitchen cabinet' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for cupboard that I've seen before include "Furniture for storing provisions etc." , "Type of cabinet" , "Storage place" , "Store for crockery etc" , "Storage unit" .)