The most common and most likely answer to this crossword clue is the 9 letter word AVOIDABLE
I've seen this crossword clue in The Guardian
A
V
O
I
D
A
B
L
E
Buddy explains!

The straight part
We know that "can be prevented" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case can be prevented = avoidable.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 AVOIDABLE mean?
AVOIDABLE noun- Something that can or should be avoided.
- Capable of being vacated; liable to be annulled or made invalid; voidable.
- Capable of being avoided, shunned, or escaped.