Sent back some people's sumptuous seafood serving (6)
I believe the answer is:
mussel
'seafood serving' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'sent back some people's sumptuous' is the wordplay.
'sent back' is a reversal indicator.
'some' indicates a hidden word (some parts of the word are used).
'lessum' is hidden within 'peoples sumptuous'.
'lessum' in reverse letter order is 'MUSSEL'.
Can you help me to learn more?
(Other definitions for mussel that I've seen before include "Black marine bivalve" , "Common bivalve shellfish, anchors to rocks" , "Black marine bivalves" , "finds power in sound" , "Edible shellfish" .)