The most common and most likely answer to this crossword clue is the 10 letter word APOSTROPHE
I've seen this crossword clue in The Guardian
A
P
O
S
T
R
O
P
H
E
More clues leading to the result APOSTROPHE
- Bloomingdale's gets one out to a shopper
- Address in Bishop’s Stortford
- Punctuation mark perhaps too irregular
- Mark small extract from Eugene O’Neill
- It’s often abused by grocers dealing with multiples
- If letters were missing, this could be the fourth character of eight in a string
- Support right in a forlorn hope – sign of lack of character?
- Punctuation mark, perhaps too complicated?
- Punctuation mark, perhaps too misused
- Pope rash to change punctuation
Buddy explains!

The straight part
We know that "punctuation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case punctuation = apostrophe.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 APOSTROPHE mean?
APOSTROPHE noun- The text character ’, which serves as a punctuation mark in various languages and as a diacritical mark in certain rare contexts.
- A sudden exclamatory piece of dialogue addressed to someone or something, especially absent.