Of the Milky Way (8)
I believe the answer is:
galactic
'of the milky way' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for galactic that I've seen before include "To do with large independent systems of stars" , "Relating to large star systems" , "More than stellar" , "Of independent system of stars in space" , "Referring to the star system" .)