The most common and most likely answer to this crossword clue is the 4 letter word RUNE
I've seen this crossword clue in Independent
R
U
N
E
More clues leading to the result RUNE
- Nice way to host knight, ancient character
- Mysterious character takes ecstasy after work
- Cuts edges off carved letter
- Work on English for Finnish song
- Mysterious character reared in the nursery
- Flee ultimately strange old character
- Manage to introduce English character
- Roobarb originally a French character
- Mystic symbol found at any number in French street
- Fifth execution of program producing mysterious character
Buddy explains!

The straight part
We know that "carved letter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case carved letter = rune.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 RUNE mean?
RUNE noun- A letter, or character, belonging to the written language of various ancient Germanic peoples, especially the Scandinavians and the Anglo-Saxons.
- A Finnish or Scandinavian epic poem, or a division of one, especially a division of the Kalevala.
- A letter or mark used as mystical or magic symbol.
- A verse or song, especially one with mystical or mysterious overtones; a spell or an incantation.
- A roun (secret or mystery).
- In the Go programming language, a Unicode code point.