The most common and most likely answer to this crossword clue is the 8 letter word INITIALS
I've seen this crossword clue in The Daily Telegraph
I
N
I
T
I
A
L
S
Buddy explains!

The straight part
We know that "Signs" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case signs = initials.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 INITIALS mean?
INITIALS noun- The first letter of a word or a name.
- In plural, the first letter of each word of a person's full name considered as a unit.
- A distinguished initial letter of a chapter or section of a document.
- Onset, part of a syllable that precedes the syllable nucleus in phonetics and phonology.
- An abbreviation of a person's name, constructed by taking the initial letters of first, last, and sometimes middle name(s). See monogram