Apple brandy and soda served up after Calvin dropped in (8)
I believe the answer is:
calvados
'apple brandy' is the definition.
(I've seen this before)
'soda served up after calvin dropped in' is the wordplay.
'served up' says the letters should be written backwards (in a down clue, letters go up).
'after' says to put letters next to each other.
'dropped' is a deletion indicator.
'soda' backwards is 'ados'.
'calvin' with 'in' removed is 'calv'.
'ados' put after 'calv' is 'CALVADOS'.
'and' acts as a link.
(Other definitions for calvados that I've seen before include "Type of apple brandy" , "drink" , "Vocal ads (anag) - apple brandy" , "Brandy distilled from apple cider" , "area near Caen" .)