Study of the stars (9)
I believe the answer is:
astronomy
'study of the stars' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for astronomy that I've seen before include "Mayors not involved in study of the stars" , "The study of celestial bodies" , "Stargazing" , "Science that deals with celestial objects" , "branch of science" .)