Place to eat trifle (4)
I believe the answer is:
mess
This clue is a double definition.
'place to eat' is the first definition.
(I've seen this before)
'trifle' is the second definition.
(thesaurus)
(Other definitions for mess that I've seen before include "Canteen - muddle" , "Where those who serve eat" , "dog's dinner" , "Mix-up" , "Untidy muddle" .)