The most common and most likely answer to this crossword clue is the 5 letter word TA-TA
I've seen this crossword clue in Financial Times
T
A
-
T
A
More clues leading to the result TA-TA
- Thanks, thanks, and goodbye
- Goodbye to All That’s leading parts are about to be cast
- Goodbye to all those armies on the front
- So long tempted and tried avocado for starters
- Cheers: cheers and cheerio
- See you make lace article
- Goodbye with repeated cheers
- A Farewell to Arms, just opened twice
- Terriers repeatedly see you
- You shouldn’t have repeated for so long …
Buddy explains!

The straight part
We know that "A Farewell" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a farewell = ta-ta.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 TA-TA mean?
TA-TA interjection- Goodbye.
- (usually plural) A woman's breast.