The most common and most likely answer to this crossword clue is the 9 letter word SINCERELY
I've seen this crossword clue in The Times
S
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More clues leading to the result SINCERELY
- Function involving clubs supported by bank — honestly
- After bank with genuine style?
- From then till now, bank with honesty
- … on account of bank in earnest
- Correspondent’s last word after bank closes
- Bank pursues wrong church in good faith
- Possible sign-off? Bank closes after that
- Seeing that bank showing honesty
- Truly evil church Count follows
- Way to end a letter because trust is needed
Buddy explains!

The straight part
We know that "honestly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case honestly = sincerely.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 SINCERELY mean?
SINCERELY adverb- In a sincere or earnest manner; honestly.
- A conventional formula for ending a letter, used when the salutation addresses the person for whom the letter is intended by his or her name.