The most common and most likely answer to this crossword clue is the 4 plus 4 letter word NEAR MISS
I've seen this crossword clue in The Daily Telegraph
N
E
A
R
M
I
S
S
More clues leading to the result NEAR MISS
- Seminars replaced meeting thankfully avoided
- Marines clashing with squadron leader — almost a catastrophe
- Local girl narrowly avoided accident
- Where teacher's pet is? That's close to bull!
- Dashed back to protect English girl from narrow escape
- Part of one arm is stuck, almost a disaster
- Close shave by girl
- Local unmarried woman narrowly avoided collision
- Complex seminars not quite hitting the mark
- Tight young lady narrowly avoided collision
Buddy explains!
The straight part
We know that "mishap that’s almost disastrous" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mishap that’s almost disastrous = near miss.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.