The most common and most likely answer to this crossword clue is the 3 letter word KIR
I've seen this crossword clue in The Guardian
K
I
R
More clues leading to the result KIR
- One in Sweden's ready for a drink
- Drink starts to kick in rapidly
- Brynner and Kerr, perhaps close to bar, drink!
- First person in 2 Kings to drink
- Old Labour leader rejecting European drink
- Scottish Church’s endless liqueur
- Endless caterwaul of bagpipes could lead one to drink
- Drink, one consumed by two Kings
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 = kir.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 KIR mean?
KIR noun- A cocktail made with a measure of crème de cassis topped up with white wine.