Antares or Betelgeuse (3,5)
I believe the answer is:
red giant
'antares or betelgeuse' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for red giant that I've seen before include "Large star nearing the end of its life" , "Cool, immense star of high luminosity" , "Large, cool bright star" , "big star" , "Large low-temperature star" .)