The most common and most likely answer to this crossword clue is the 8 letter word LIBATORY
I've seen this crossword clue in The Guardian
L
I
B
A
T
O
R
Y
Buddy explains!
The straight part
We know that "Relating to drink/Relating to drink" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case relating to drink/relating to drink = libatory.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.