The most common and most likely answer to this crossword clue is the 3 letter word SUP
I've seen this crossword clue in Financial Times
S
U
P
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 = sup.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 SUP mean?
SUP noun- A sip; a small amount of food or drink.
- To sip; to take a small amount of food or drink into the mouth, especially with a spoon.
- To take supper.
- What's up (either as a greeting or actual question)
- Being or relating to the squark that is the superpartner of an up quark.
- Superintendent.
- Upper limit.
- A stand-up paddleboard