The most common and most likely answer to this crossword clue is the 10 letter word DEATHWATCH
I've seen this crossword clue in Financial Times
D
E
A
T
H
W
A
T
C
H
More clues leading to the result DEATHWATCH
Buddy explains!

The straight part
We know that "Beetle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case beetle = deathwatch.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 DEATHWATCH mean?
DEATHWATCH noun- A vigil beside a dying person
- One who guards a condemned person before execution.
- A deathwatch beetle.