Party drink to sink after picking up a snail? (9)
I believe the answer is:
gastropod
'a snail?' is the definition.
(snail is a kind of gastropod)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for gastropod that I've seen before include "Escargot" , "Eg, a snail or slug" , "Shellfish" , "Mollusc such as snail or limpet" , "Could be snail" .)