The most common and most likely answer to this crossword clue is the 9 letter word EVACUATES
I've seen this crossword clue in The Times
E
V
A
C
U
A
T
E
S
Buddy explains!

The straight part
We know that "empties" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case empties = evacuates.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 EVACUATES mean?
EVACUATES verb- To leave or withdraw from; to quit; to retire from
- To cause to leave or withdraw from.
- To make empty; to empty out; to remove the contents of, including to create a vacuum.
- To make empty; to deprive.
- To remove; to eject; to void; to discharge, as the contents of a vessel, or of the bowels.
- To make void; to nullify; to vacate.