The most common and most likely answer to this crossword clue is the 8 letter word MISRULED
M
I
S
R
U
L
E
D
More clues leading to the result MISRULED
Buddy explains!

The straight part
We know that "Failed to manage" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case failed to manage = misruled.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.
Crossword Answer definitions
MISRULED verb- Of a trial judge, to make a bad decision in court.
- To rule badly; to misgovern.