Tailed celestial body (5)
I believe the answer is:
comet
'tailed celestial body' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for comet that I've seen before include "Celestial orbiter" , "Heavenly body with a fiery tail" , "Tailed space traveller" , "Halley's phenomenon in space" , "Halley's space traveller?" .)