Meal at which people help themselves (6)
I believe the answer is:
buffet
'meal at which people help themselves' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for buffet that I've seen before include "cafeteria?" , "Refreshment bar" , "Wallop" , "Bang - refreshment counter" , "Blow - self-service food" .)