Certainly you expect soup to begin with (3)
I believe the answer is:
yes
'certainly' is the definition.
(both can be used to answer in the affirmative)
'you expect soup to begin with' is the wordplay.
'to begin with' says to take the initial letters.
The first letters of 'you expect soup' is 'YES'.
(Other definitions for yes that I've seen before include "Of course" , "Validating vote" , "Agreed" , "Certainly!" , "Oui" .)