The most common and most likely answer to this crossword clue is the 6 letter word SACRAL
S
A
C
R
A
L
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The straight part
We know that "of bones" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case of bones = sacral.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 SACRAL mean?
SACRAL noun- Any of the sacral bones that make up the sacrum.
- Of the sacrum.
- Sacred.