The most common and most likely answer to this crossword clue is the 7 letter word GOODBYE
I've seen this crossword clue in Financial Times
G
O
O
D
B
Y
E
More clues leading to the result GOODBYE
- See you bargain soundly
- Farewell bargain announced
- Leaving fair purchase on the 20?
- Take off close in poem – it’s so long
- The last word in virtue: and extra
- I’m off to travel round Germany via Spain
- Bargain reported for so long
- I’m going to depart, body failing, end of life
- Grow old, regularly missing extra aparting
- Bargain by the sound of it? I’m off!
Buddy explains!

The straight part
We know that "Leaving" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case leaving = goodbye.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 GOODBYE mean?
GOODBYE noun- An utterance of goodbye, the wishing of farewell to someone.
- To say goodbye; to wish somebody farewell on parting.
- Farewell; a formula used to another person or persons when the speaker, writer, or person addressed is departing.