The most common and most likely answer to this crossword clue is the 6 letter word SUDDEN
I've seen this crossword clue in Independent
S
U
D
D
E
N
More clues leading to the result SUDDEN
- Theologian, ’e’s wearing a red top? That’s unexpected
- Unexpected upset after university ousts adult
- Not expected to be thrown back in abandoned dustbin
- Odd bits of sound study rather unexpected
- Unexpected retreat in the south of France?
- Swift in South of France hidey-hole
- African country rejecting a new place for lions? That’s unexpected
- Making south of France home. That’s unforeseen
- Without warning, nudes burst out. Around 500!
- Sharp reflection in reshined dustpan
Buddy explains!

The straight part
We know that "unexpected" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unexpected = sudden.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 SUDDEN mean?
SUDDEN noun- An unexpected occurrence; a surprise.
- Happening quickly and with little or no warning.
- Hastily prepared or employed; quick; rapid.
- Hasty; violent; rash; precipitate.
- Suddenly.