'Stuff it!' — Queen unhappily entertaining Johnson (9)
I believe the answer is:
equipment
'stuff' is the definition.
(I've seen this before)
'it queen unhappily entertaining johnson' is the wordplay.
'unhappily' indicates anagramming the letters.
'entertaining' is an insertion indicator.
'johnson' becomes 'pm' (prime minister Boris Johnson).
'it'+'queen'='itqueen'
'itqueen' with letters rearranged gives 'equient'.
'equient' going around 'pm' is 'EQUIPMENT'.
(Other definitions for equipment that I've seen before include "Apparatus, gear" , "Apparatus, tools" , "Kit, apparatus" , "Set of instruments that perform a service" , "4 [TACKLE]" .)