The most common and most likely answer to this crossword clue is the 8 letter word CREEPIER
I've seen this crossword clue in The Guardian
C
R
E
E
P
I
E
R
More clues leading to the result CREEPIER
Buddy explains!

The straight part
We know that "more scary" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case more scary = creepier.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 CREEPIER mean?
CREEPIER adjective- Moving by creeping along.
- Producing an uneasy fearful sensation, as of things crawling over one's skin.
- Feeling an uneasy fearful sensation; creeped out.
- Strangely repulsive.