The most common and most likely answer to this crossword clue is the 5 plus 8 letter word TABLE FOOTBALL
I've seen this crossword clue in The Guardian
T
A
B
L
E
F
O
O
T
B
A
L
L
Buddy explains!
The straight part
We know that "where bars have swingers who score" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case where bars have swingers who score = table football.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.