Pearl's maternal parent (5)
I believe the answer is:
nacre
This might be a double definition.
'pearl's' is the first definition.
(nacre is another name for mother-of-pearl)
'maternal parent' is the second definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
Can you help me to learn more?
(Other definitions for nacre that I've seen before include "Mother-of-pearl from shellfish" , "Mother of pearl" , "valuable material" , "inside of shell" , "Mother-of-pearl - crane (anag)" .)