The most common and most likely answer to this crossword clue is the 7 letter word EPISTLE
I've seen this crossword clue in Independent
E
P
I
S
T
L
E
More clues leading to the result EPISTLE
- Foreign letter coming in is the French letter
- Message from ref's signal having extended play where first couple are sent off
- Letter tiles thrown out after Scrabble championship finally?
- Letter showing way inside English mansion
- Communication left in European skiing area
- Message left in European skiing area
- Message from turbulent Split received in central Greece
- I step out to get the French letter
- Most impressive! Let’s reread communication
- Letter is inept, might you say? Literally embarrassing for starters
Buddy explains!

The straight part
We know that "Message" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case message = epistle.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 EPISTLE mean?
EPISTLE noun- A letter, or a literary composition in the form of a letter.
- One of the letters included as a book of the New Testament.
- To write; to communicate in a letter or by writing.