The most common and most likely answer to this crossword clue is the 5 letter word SIKES
I've seen this crossword clue in The Times
S
I
K
E
S
More clues leading to the result SIKES
Buddy explains!

The straight part
We know that "Malevolent character" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case malevolent character = sikes.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 SIKES mean?
SIKES noun- A gutter or ditch; a small stream that frequently dries up in the summer.
- A sigh.
- To sigh or sob.