The most common and most likely answer to this crossword clue is the 8 letter word BOTCH-UP
I've seen this crossword clue in The Guardian
B
O
T
C
H
-
U
P
Buddy explains!
The straight part
We know that "failure" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case failure = botch-up.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 BOTCH-UP mean?
BOTCH-UP noun- A botched job.