Rejected elements of model art, say, like stars (6)
I believe the answer is:
astral
'like stars' is the definition.
(astral means relating to stars)
'rejected elements of model art say' is the wordplay.
'rejected' is a reversal indicator.
'elements of' indicates a hidden word (elements or parts of the clue).
'lartsa' can be found hidden inside 'model art say'.
'lartsa' backwards is 'ASTRAL'.
(Other definitions for astral that I've seen before include "like a star" , "Pertaining to the stars" , "Relating to stars" , "Universal" , "Related to the stars" .)