Something big in the drink — a drink swallowed by idiot (8)
I believe the answer is:
cachalot
'something big in the drink' is the definition.
I can't tell whether this definition defines the answer.
'a drink swallowed by idiot' is the wordplay.
'drink' becomes 'cha' (cha can mean tea).
'swallowed by' indicates putting letters inside.
'idiot' becomes 'clot' (both can mean a stupid person).
'a'+'cha'='acha'
'acha' going into 'clot' is 'CACHALOT'.
Can you help me to learn more?
(Other definitions for cachalot that I've seen before include "Being in sea" , "Large sperm whale" , "Beast" , "In the main I spout" .)