The most common and most likely answer to this crossword clue is the 6 letter word INCUBI
I
N
C
U
B
I
More clues leading to the result INCUBI
- Demons one youngster encountered in Northern Ireland
- Fiends in India trapping small bear
- Night-time threats to females
- Nightmarish males occupying certain cubicles
- Demons? Fashionable young reporter has one
- Concerned with young one’s nightmares
- New copper to book setter, after same reveals
- Trendy art movement’s lost manuscript raised spirits
- Smart young reporter, one causing nightmares
- Fashionable young one’s current demons
Buddy explains!

The straight part
We know that "demons" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case demons = incubi.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 INCUBI mean?
INCUBI noun- An evil spirit supposed to oppress people while asleep, especially to have sex with women as they sleep.
- A feeling of oppression during sleep, sleep paralysis; night terrors, a nightmare.
- (by extension) Any oppressive thing or person; a burden.
- One of various of parasitic insects, especially subfamily Aphidiinae.