The most common and most likely answer to this crossword clue is the 4 plus 2 plus 5 letter word KISS OF DEATH
I've seen this crossword clue in The Daily Telegraph
K
I
S
S
O
F
D
E
A
T
H
More clues leading to the result KISS OF DEATH
- Mouth-to-mouth resuscitation? On the contrary
- Unfortunately, Ofsted has killed inspirational leaders, the final nail in the coffin?
- So it’s not mouth-to-mouth resuscitation?
- Do shake fist about cause of failure
- Recipe for disaster in affectionate gesture by horseman?
- OK, shifted as ordered but it’s sure to fail
Buddy explains!
The straight part
We know that "cause of failure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cause of failure = kiss of 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.