The most common and most likely answer to this crossword clue is the 7 plus 3 letter word SEALING WAX
I've seen this crossword clue in The Daily Telegraph
S
E
A
L
I
N
G
W
A
X
More clues leading to the result SEALING WAX
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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 SEALING WAX mean?
SEALING WAX noun- Wax formerly melted onto a letter to seal it; the picture of the sender's seal was often pressed into the wax as evidence that the letter had not been opened.