The most common and most likely answer to this crossword clue is the 10 letter word OVERSLEEPS
I've seen this crossword clue in The Guardian
O
V
E
R
S
L
E
E
P
S
More clues leading to the result OVERSLEEPS
Buddy explains!

The straight part
We know that "perhaps fails to respond to alarm" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case perhaps fails to respond to alarm = oversleeps.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 OVERSLEEPS mean?
OVERSLEEPS verb- To sleep for longer than intended.
- To sleep for longer than one intended.
- To sleep beyond (a given time), to sleep through (an event etc.).