The most common and most likely answer to this crossword clue is the 7 letter word SUCCUBI
I've seen this crossword clue in The Times
S
U
C
C
U
B
I
Buddy explains!

The straight part
We know that "Devils" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case devils = succubi.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 SUCCUBI mean?
SUCCUBI noun- A female demon which comes to men, especially monks, in their dreams to seduce them and have sexual intercourse, drawing energy from the men to sustain themselves, often until the point of exhaustion or death.
- A strumpet, whore or prostitute.