The most common and most likely answer to this crossword clue is the 6 letter word MESCAL
I've seen this crossword clue in The Daily Telegraph
M
E
S
C
A
L
More clues leading to the result MESCAL
Buddy explains!

The straight part
We know that "drink from Mexico" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case drink from mexico = mescal.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 MESCAL mean?
MESCAL noun- A Mexican alcoholic drink distilled from the fermented juice of the agave.
- The peyote cactus.