The most common and most likely answer to this crossword clue is the 5 letter word HEXED
I've seen this crossword clue in The Guardian
H
E
X
E
D
More clues leading to the result HEXED
Buddy explains!
The straight part
We know that "Spellbound" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spellbound = hexed.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 HEXED mean?
HEXED verb- To cast a spell on (specifically an evil spell), to bewitch.
- Cursed; afflicted with bad luck.