The most common and most likely answer to this crossword clue is the 6 letter word FIASCO
I've seen this crossword clue in Financial Times
F
I
A
S
C
O
More clues leading to the result FIASCO
- As if failed, company in state of disorder
- Following one, a second business failure
- Bomber following one in the role of peace protester
- Disaster, a boat docked if reversing at first
- Backing needed, if and when county is a failure
- Girl’s firm, concealing a catastrophe
- Motor-racing company accepting a second disaster
- As if alternative company could be a complete disaster
- Grand Prix race track in Berkshire unfinished? What a debacle!
- Provided backing before a small company becomes failure
Buddy explains!

The straight part
We know that "shambles" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shambles = fiasco.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 FIASCO mean?
FIASCO noun- A sudden or unexpected failure.
- A ludicrous or humiliating situation. Some effort that went quite wrong.
- A wine bottle in a (usually straw) jacket.