Last sign (6)
I believe the answer is:
pisces
'last sign' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pisces that I've seen before include "The twelfth sign of the zodiac, the fishes" , "Twelfth sign of the zodiac, the Fish" , "Twelfth zodiacal sign" , "stars" , "'Sign of the zodiac, the fish (6)'" .)