The most common and most likely answer to this crossword clue is the 9 letter word KANGAROOS
I've seen this crossword clue in The Daily Telegraph
K
A
N
G
A
R
O
O
S
More clues leading to the result KANGAROOS
- Rage and regrets apparently after a thousand jumpers
- Undo anoraks, go for jumpers
- Rugby team become jerks when driving
- Jerks go out with anoraks
- Ok, a sarong is designed for animals down under
- Animals go on Ark as arranged
- Jumpers and anoraks go tatty
- Hopping animals accidentally sank Argo around the middle of October
- Bats go on ark as representatives of the mammals
Buddy explains!

The straight part
We know that "Jumpers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case jumpers = kangaroos.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 KANGAROOS mean?
KANGAROOS noun- A member of the Macropodidae family of large marsupials with strong hind legs for hopping, native to Australia.
- A hooded jacket with a front pocket, usually of fleece material, a kangaroo jacket.
- To practice kangaroo care on an infant; to hold a premature infant against the skin.
- To hunt kangaroo.
- To move like a kangaroo