The eleventh sign of the Zodiac (8)
I believe the answer is:
aquarius
'the eleventh sign of the zodiac' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for aquarius that I've seen before include "A 23 ac" , "The Water Bearer" , "Sign of the zodiac, the water-bearers" , "Eleventh sign of the Zodiac" , "Star sign" .)