Everyone in dining room denied starter (3)
I believe the answer is:
all
'everyone' is the definition.
(all people)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for all that I've seen before include "'... things come to those who wait'" , "'Bless 'em - - ' (song)" , "without exception" , "Everybody; everything" , "Garden path (Fr.)" .)