God thus climbing above goddess (6)
I believe the answer is:
osiris
'god' is the definition.
(Osiris is an example)
'thus climbing above goddess' is the wordplay.
'thus' becomes 'so' ('so' can be a synonym of 'thus').
'climbing' says the letters should be written backwards (in a down clue, letters climb up).
'above' means one lot of letters go next to another.
'goddess' becomes 'iris' (goddess of the rainbow).
'so' in reverse letter order is 'os'.
'os'+'iris'='OSIRIS'
(Other definitions for osiris that I've seen before include "once highly esteemed by Egyptians" , "underworld boss" , "Egyptian god, father of Horus" , "Egyptian god - sis or I (anag)" , "one Egyptians worshipped" .)