The most common and most likely answer to this crossword clue is the 9 letter word KILOLITRE
I've seen this crossword clue in Independent
K
I
L
O
L
I
T
R
E
More clues leading to the result KILOLITRE
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.
Crossword Answer definitions
KILOLITRE noun- A unit of volume equivalent to 1000 litres, and equal to one cubic metre of water. Symbol: kl