Short sweet dish alternatively known as main course (8)
I believe the answer is:
moussaka
'main course' is the definition.
(I've seen this before)
'short sweet dish alternatively' is the wordplay.
'short' means to remove the last letter.
'sweet' becomes 'mousse' (type of dessert or sweet).
'dish alternatively' becomes 'aka' (I am not sure about this - if you are sure you should believe this answer much more).
'mousse' with its last letter taken away is 'mouss'.
'mouss'+'aka'='MOUSSAKA'
'known as' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for moussaka that I've seen before include "Greek dish of layers of minced meat, aubergine etc topped with cheese sauce" , "Dish of minced lamb with aubergines in a white sauce" , "Greek aubergine-based dish" , "a Greek speciality" , "Greek dish of lamb and aubergine" .)