The most common and most likely answer to this crossword clue is the 8 letter word CONTRAIL
I've seen this crossword clue in The Daily Telegraph
C
O
N
T
R
A
I
L
Buddy explains!

The straight part
We know that "Jumbo might leave this" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case jumbo might leave this = contrail.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 CONTRAIL mean?
CONTRAIL noun- An artificial cloud made by the exhaust of jet aircraft or wingtip vortices that precipitate a stream of tiny ice crystals in moist, frigid upper air.