Leo, for example (13)
(Other definitions for constellation that I've seen before include "Formation of stars" , "E.g Orion, Andromeda" , "Client to salon (anag.)" , "Twins, perhaps" , "Cassiopeia, for example" .)
'leo for example' is the definition.
(I know that Leo is a star sign)
This is all the clue.
(Other definitions for star sign that I've seen before include "Astrological symbol" , "Astrological house" , "One area into which the zodiac is divided" , "Leo perhaps" , "Leo, for example" .)