Impressionist art, featuring heavenly body (4)
I believe the answer is:
star
'heavenly body' is the definition.
(star is a kind of heavenly body)
'impressionist art featuring' is the wordplay.
'featuring' indicates a hidden word.
'STAR' can be found hidden inside 'impressionist art'.
(Other definitions for star that I've seen before include "It twinkles" , "Main attraction" , "Sign of a leading performer" , "Brilliant performer?" , "Brilliant person" .)