The most common and most likely answer to this crossword clue is the 5 letter word ABYSM
I've seen this crossword clue in Financial Times
A
B
Y
S
M
More clues leading to the result ABYSM
- Tips for swim past rocky bay in gulf
- Baby’s mum wiping bottom – not something one could get out of!
- In Siberia, by small crevasse
- Bother includes this for new parent – it’s bottomless
- An annoying Scotswoman heard in this pit
- Bottomless pit used by baby’s mother
- Bottomless pit revealed by baby’s mouth
- Baby’s motherland somewhere in Gulf? Just the opposite
- Fancy embassy quarter disappears into a bottomless pit
- Gulf or bay most often polluted
Buddy explains!

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 ABYSM mean?
ABYSM noun- Hell; the infernal pit; the great deep; the primal chaos.
- An abyss; a gulf, a chasm, a very deep hole.