The most common and most likely answer to this crossword clue is the 5 plus 4 plus 5 letter word DICES WITH DEATH
I've seen this crossword clue in The Daily Telegraph
D
I
C
E
S
W
I
T
H
D
E
A
T
H
Buddy explains!
The straight part
We know that "lives very dangerously" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case lives very dangerously = dices with death.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.