Precious object Nemo gets at sea (8)
I believe the answer is:
gemstone
'precious object' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'nemo gets at sea' is the wordplay.
'at sea' indicates anagramming the letters.
'nemo'+'gets'='nemogets'
'nemogets' with letters rearranged gives 'GEMSTONE'.
Can you help me to learn more?
(Other definitions for gemstone that I've seen before include "something of great value" , "It's considered precious" , "[RUBY] , for example" , "Sparkler" , "Eg, sapphire" .)