Lustrous greyish wild crane (5)
I believe the answer is:
nacre
'lustrous greyish wild crane' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'wild crane' is the wordplay.
'wild' indicates an anagram.
'crane' anagrammed gives 'NACRE'.
Can you help me to learn more?
(Other definitions for nacre that I've seen before include "Constituent of inlay furniture" , "valuable material" , "inside of shell" , "Pearl's mum" , "Mother-of-pearl - crane (anag)" .)