Astronomer (9)
I believe the answer is:
stargazer
'astronomer' is the definition.
(I know that astronomer can be written as stargazer)
This is the entire clue.
(Other definitions for stargazer that I've seen before include "Looker-up at night" , "Astronomer, or dreamer" , "Astronomer or astrologer" , "One looks up" , "I look at the Sun" .)