A sign of a poisonous insect (7)

I believe the answer is:

scorpio

I'm a little stuck... Click here to teach me more about this clue!

'a sign' is the definition.
(sign of the zodiac)

I don't understand how the remainder of the clue works.

(Other definitions for scorpio that I've seen before include "Oct-Nov zodiac sign" , "Person born between 23 October and 22 November?" , "Sign of stinging arachnid" , "Eighth sign of the Zodiac, kind of spider" , "Stinger" .)

I've seen this clue in The Globe and Mail.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.