The eighth sign of the zodiac (7)
I believe the answer is:
scorpio
'the eighth sign of the zodiac' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for scorpio that I've seen before include "star group" , "Oct - Nov zodiac sign" , "Eight sign of Zodiac, of arachnid family" , "Eighth sign of the Zodiac, kind of spider" , "Oct-Nov zodiac sign" .)