The most common and most likely answer to this crossword clue is the 8 letter word UNSETTLE
I've seen this crossword clue in The Times
U
N
S
E
T
T
L
E
More clues leading to the result UNSETTLE
- Peacekeepers resolve trouble
- Upset one on bench
- Uncontrolled teen lust is to cause restlessness
- University upset about son causing bother
- End of day, not start – story not a bother
- Rattle and shake lunettes
- A Parisian somewhere in North Yorkshire is upset
- Lunettes cracked – bother!
- Disturb tutees with Latin noun, irregular
- Worry
Buddy explains!
The straight part
We know that "cause restlessness" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cause restlessness = unsettle.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 UNSETTLE mean?
UNSETTLE verb- To make upset or uncomfortable
- To bring into disorder or disarray