Pasta dish ruined alas and starter of guacamole not available (7)
I believe the answer is:
lasagna
'pasta dish' is the definition.
(dish of lasagna pasta)
'ruined alas and starter of guacamole not available' is the wordplay.
'ruined' indicates anagramming the letters.
'and' means one lot of letters go next to another.
'starter of' says to take the initial letters.
'not available' becomes 'na' (abbreviation).
The first letter of 'guacamole' is 'g'.
'alas' with letters rearranged gives 'lasa'.
'lasa'+'g'+'na'='LASAGNA'
(Other definitions for lasagna that I've seen before include "Italian food" , "Calorie-rich food" , "Broad flat pasta" , "pasta's provided" , "Baked pasta dish" .)