The most common and most likely answer to this crossword clue is the 7 letter word PARLOUS
I've seen this crossword clue in The Daily Telegraph
P
A
R
L
O
U
S
Buddy explains!

The straight part
We know that "Dangerous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dangerous = parlous.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 PARLOUS mean?
PARLOUS adjective- Attended with peril; dangerous, risky.
- Appalling, dire, terrible.
- Dangerously clever or cunning; also, remarkably good or unusual.
- Extremely, very.