Incredibly remote extraterrestrial object (6)
I believe the answer is:
meteor
'extraterrestrial object' is the definition.
(I know that meteor is a type of extraterrestrial object)
'incredibly remote' is the wordplay.
'incredibly' indicates anagramming the letters.
'remote' anagrammed gives 'METEOR'.
(Other definitions for meteor that I've seen before include "Component of shower" , "streaker?" , "Small piece of matter in the solar system" , "Solar System body" , "Glowing body entering atmosphere" .)