The most common and most likely answer to this crossword clue is the 7 letter word HASHTAG
I've seen this crossword clue in The Sunday Telegraph
H
A
S
H
T
A
G
More clues leading to the result HASHTAG
- Link to a theme involves witch’s crossing close to midnight
- Husband aghast having to change label for topic
- One identifying Twitter topic that has Henry reeling, aghast
- Twitter indicator has reversed section of raga
- Social media feature – dice game for children
- Means of following online drug trail
- New style identification has revolutionised biblical city
- Label dish with game
- Mess that’s ending with a good link to tweet
- Leader of House aghast on being ridiculed in Internet identifier
Buddy explains!
The straight part
We know that "Label" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case label = hashtag.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 HASHTAG mean?
HASHTAG noun- A metadata tag, signaled by a preceding hash sign (#), used to label content.
- The hash sign itself.
- To label (a message) with a hashtag.