Celestial body's surreal, regular revolution of the sun (6)
I believe the answer is:
uranus
'celestial body's' is the definition.
(Uranus is an example)
'surreal regular revolution of the sun' is the wordplay.
'regular' means one should take alternating letters.
'revolution of' is an anagram indicator (I've seen 'revolution' mean this).
The alternate letters of 'surreal' are 'ura'.
'sun' with letters rearranged gives 'nus'.
'ura'+'nus'='URANUS'
(Other definitions for uranus that I've seen before include "Planet discovered in 1781 by Herschel" , "Seventh rock from the sun?" , "USA urn on major planet" , "Seventh planet from the sun" , "Uses profane language" .)