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 in reverse (in a down clue, going upwards).
'after' is a charade indicator (letters next to each other).
'dropped' suggests deleting specific letters.
'soda' in reverse letter order is 'ados'.
'calvin' with 'in' taken out is 'calv'.
'ados' after 'calv' is 'CALVADOS'.
'and' is the 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" .)