The most common and most likely answer to this crossword clue is the 5 letter word ANTRA
A
N
T
R
A
More clues leading to the result ANTRA
- Cavities in human trachea
- Body cavities physician trapanned – look inside
- Hollow areas in the Appalachian Trail
- Body cavities found in ruminant? Rarely
- Regularly hasn’t tartar or cavities
- Sinuses of man transplanted
- Bodily cavities conserved by organ transplant
- Fan tracery includes empty spaces
- Seductress’s out of bounds chambers
Buddy explains!

The straight part
We know that "empty spaces" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case empty spaces = antra.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 ANTRA mean?
ANTRA noun- A bodily cavity, especially one having bony walls, especially one in the sinuses.