Shape or tint heavenly body (6)
I believe the answer is:
triton
'heavenly body' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'shape or tint' is the wordplay.
'shape' indicates anagramming the letters.
'or'+'tint'='ortint'
'ortint' is an anagram of 'TRITON'.
Can you help me to learn more?
(Other definitions for triton that I've seen before include "heavenly conch-blower" , "Moon" , "Satellite of Neptune - minor sea god" , "Greek minor sea-god with trident, fish-tail and shell trumpet" , "Trot in after sea-god, son of Poseidon" .)