The most common and most likely answer to this crossword clue is the 7 letter word RICKETY
R
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C
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Y
Buddy explains!
The straight part
We know that "in danger of breakdown" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in danger of breakdown = rickety.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 RICKETY mean?
RICKETY adjective- Of an object: not strong or sturdy, as because of poor construction or upkeep; not safe or secure.
- Of a person: feeble in the joints; tottering.
- Affected with or suffering from rickets.