First sausages and potato purée then punch - a great success! (5,3)
I believe the answer is:
smash hit
'a great success' is the definition.
(I've seen this before)
'first sausages and potato puree then punch' is the wordplay.
'first sausages' becomes 's' (mst letter of 'sausages').
'and' is a charade indicator (letters next to each other).
'potato puree' becomes 'mash' (I can't explain this - if you can you should believe this answer much more).
'then' says to put letters next to each other.
'punch' becomes 'hit'.
's'+'mash'+'hit'='SMASH-HIT'
Can you help me to learn more?
(Other definitions for smash hit that I've seen before include "Major success" , "great entertainment" , "number one" , "Great success" , "successful play?" .)