The most common and most likely answer to this crossword clue is the 12 letter word ENDANGERMENT
I've seen this crossword clue in The Sunday Telegraph
E
N
D
A
N
G
E
R
M
E
N
T
More clues leading to the result ENDANGERMENT
Buddy explains!

The straight part
We know that "put at risk" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case put at risk = endangerment.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 ENDANGERMENT mean?
ENDANGERMENT noun- The act of putting someone into danger, or the condition of being in danger.
- The exposure of someone, especially a child, to danger or harm.