The editor's disturbed by a heavenly body (8)
I believe the answer is:
asteroid
'heavenly body' is the definition.
(asteroid is a kind of heavenly body)
'the editor's disturbed by a' is the wordplay.
'disturbed' indicates anagramming the letters.
'by' is a charade indicator (letters next to each other).
'editors' with letters rearranged gives 'steroid'.
'steroid' put after 'a' is 'ASTEROID'.
(Other definitions for asteroid that I've seen before include "could be dangerous for astronauts" , "Bit of rock that moves around the heavens" , "Bits of rock that move around the heavens" , "Small planet orbiting the Sun" , "circling rock" .)