The most common and most likely answer to this crossword clue is the 13 letter word RIGHT-WINGERS
I've seen this crossword clue in Financial Times
R
I
G
H
T
-
W
I
N
G
E
R
S
Buddy explains!
The straight part
We know that "Blues" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case blues = right-wingers.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 RIGHT-WINGERS mean?
RIGHT-WINGERS noun- A person who belongs to the political right.
- A member of the right wing of a party or group.
- A winger who plays on the right.