The most common and most likely answer to this crossword clue is the 8 letter word CABBAGES
I've seen this crossword clue in The Daily Telegraph
C
A
B
B
A
G
E
S
More clues leading to the result CABBAGES
Buddy explains!

The straight part
We know that "Leaves" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case leaves = cabbages.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 CABBAGES mean?
CABBAGES noun- An edible plant (Brassica oleracea var. capitata) having a head of green leaves.
- The leaves of this plant eaten as a vegetable.
- A person with severely reduced mental capacities due to brain damage.
- Used as a term of endearment.
- Money.
- Marijuana leaf, the part that is not smoked but from which cannabutter can be extracted.
- The terminal bud of certain palm trees, used for food.
- The cabbage palmetto (Sabal palmetto), a palm of the southeastern US coasts and nearby islands.
- To form a head like that of the cabbage.
- To do nothing; to idle; veg out.
- To purloin or embezzle; to pilfer, to steal.