The most common and most likely answer to this crossword clue is the 8 letter word CLEAVAGE
I've seen this crossword clue in The Guardian
C
L
E
A
V
A
G
E
More clues leading to the result CLEAVAGE
- Visible split in chest, or short split in coop
- Split from company at first, taking holiday, pocketing a grand
- Bristol Channel, or Silicon Valley after augmentation?
- Bristol Channel?
- Gap between outstanding features of holiday mostly in prison
- Valley where short holiday taken in prison
- Go shortly into jail that’s split down the middle
- Almost go in prison in Split, due to bust?
- Top of chest, part receiving admiring glances, for starters
- Conservative must have consent to hoard silver for separation
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 CLEAVAGE mean?
CLEAVAGE noun- The act of cleaving or the state of being cleft.
- The hollow or separation between a woman's breasts, especially as revealed by a low neckline.
- (by extension) Any similar separation between two body parts, such as the buttocks or toes.
- The repeated division of a cell into daughter cells after mitosis.
- The splitting of a large molecule into smaller ones.
- The tendency of a crystal to split along specific planes.
- The division of voters into voting blocs.