Dining room in home's sumptuous (4)
I believe the answer is:
mess
'dining room' is the definition.
(I know that mess is a type of dining room)
'in home's sumptuous' is the wordplay.
'in' says the answer is hidden in the clue.
'MESS' is hidden within 'homes sumptuous'.
(Other definitions for mess that I've seen before include "Army dining room" , "Mix-up" , "State of disorder" , "Where military personnel eat" , "Where those who serve eat" .)