Alas, terrible note on dish (5)
I believe the answer is:
salad
'dish' is the definition.
(type of meal or dish)
'alas terrible note on' is the wordplay.
'terrible' indicates anagramming the letters.
'note' becomes 'd' (musical note).
'on' is a charade indicator (letters next to each other).
'alas' with letters rearranged gives 'sala'.
'sala'+'d'='SALAD'
(Other definitions for salad that I've seen before include "Green, potato, Russian or Waldorf?" , "Counter serving cold vegetable dishes" , "Cold vegetable dish" , "Mainly raw cold dish" , "Cold dish of various vegetables," .)