The most common and most likely answer to this crossword clue is the 9 letter word DYSPHORIA
I've seen this crossword clue in The Guardian
D
Y
S
P
H
O
R
I
A
Buddy explains!

The straight part
We know that "Uneasiness" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case uneasiness = dysphoria.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 DYSPHORIA mean?
DYSPHORIA noun- A state of feeling unwell or unhappy; a feeling of emotional and mental discomfort and suffering from restlessness, malaise, depression or anxiety.