Celebrate in song after the end of shambolic eatery (9)
I believe the answer is:
cafeteria
'eatery' is the definition.
(thesaurus)
'celebrate in song after the end of shambolic' is the wordplay.
'celebrate' becomes 'fete' ('fete' can be a synonym of 'celebrate').
'in' is an insertion indicator.
'song' becomes 'aria' (aria is a kind of song).
'after' is a charade indicator (letters next to each other).
'the end of' indicates one should take the final letters.
The final letter of 'shambolic' is 'c'.
'fete' inserted inside 'aria' is 'afeteria'.
'afeteria' put after 'c' is 'CAFETERIA'.
(Other definitions for cafeteria that I've seen before include "Canteen" , "Where one scoffs" , "Self-service restaurant" , "where food can be picked up" , "dining-room" .)