The most common and most likely answer to this crossword clue is the 3 letter word NOG
I've seen this crossword clue in The Times
N
O
G
Buddy explains!

The straight part
We know that "drink" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case drink = nog.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does NOG mean?
NOG noun- A wooden block, the size of a brick, built into a wall, as a hold for the nails of woodwork.
- One of the square logs of wood used in a pile to support the roof of a mine.
- A treenail to fasten the shores.
- To fill in, as between scantling, with brickwork.
- To fasten, as shores, with treenails.
- Short for noggin.
- A beverage based on milk, eggs, sugar, and nutmeg; often made alcoholic with rum, brandy or whisky; popular at Christmas.
- A kind of strong ale.
- A dark-skinned person; nig-nog.
- A Vietnamese person.