The most common and most likely answer to this crossword clue is the 14 letter word SPINE-CHILLING
I've seen this crossword clue in The Times
S
P
I
N
E
-
C
H
I
L
L
I
N
G
Buddy explains!

The straight part
We know that "Making uneasy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case making uneasy = spine-chilling.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 SPINE-CHILLING mean?
SPINE-CHILLING adjective- Inducing fear or nervousness; frequently used of a work of fiction.