The most common and most likely answer to this crossword clue is the 6 plus 7 letter word ALFRED DREYFUS
I've seen this crossword clue in The Guardian
A
L
F
R
E
D
D
R
E
Y
F
U
S
Buddy explains!
The straight part
We know that "Historical victim of prejudice" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case historical victim of prejudice = alfred dreyfus.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.