Celestial body — object realigned, unseen — nothing odd in that (10)
I believe the answer is:
betelgeuse
'celestial body' is the definition.
(Betelgeuse is a star)
'object realigned unseen nothing odd in that' is the wordplay.
'nothing odd in that' means one should take alternating letters (letters in odd-numbered positions are removed).
'object'+'realigned'+'unseen'='objectrealignedunseen'
The alternating letters of 'objectrealignedunseen' are 'BETELGEUSE'.
(Other definitions for betelgeuse that I've seen before include "Bright star" , "Reddish star in Orion" .)