The most common and most likely answer to this crossword clue is the 6 letter word JINXED
I've seen this crossword clue in The Guardian
J
I
N
X
E
D
Buddy explains!

The straight part
We know that "brought bad luck" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case brought bad luck = jinxed.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 JINXED mean?
JINXED verb- To cast a spell on.
- To bring bad luck to.
- To cause something to happen by mentioning it, usually sarcastically.