The most common and most likely answer to this crossword clue is the 6 letter word BOOZER
I've seen this crossword clue in The Times
B
O
O
Z
E
R
Buddy explains!

The straight part
We know that "pub" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pub = boozer.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 BOOZER mean?
BOOZER noun- One who drinks habitually; a drunkard.
- A public house, pub.
- A World War II fighter radar detector, fitted to British bombers.
- A vehicle equipped with tanks for supplying water to remote locations.