The most common and most likely answer to this crossword clue is the 12 letter word COURAGEOUSLY
I've seen this crossword clue in The Daily Telegraph
C
O
U
R
A
G
E
O
U
S
L
Y
Buddy explains!
The straight part
We know that "not deterred by danger" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not deterred by danger = courageously.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 COURAGEOUSLY mean?
COURAGEOUSLY adverb- In a courageous manner; bravely; boldly.