One of dozens that would be pure gold (5)
I believe the answer is:
carat
'one of dozens that would be pure gold' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'one of' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'a' (a thing is one thing) and 'a' is located in the answer.
The remaining letters 'crat' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for carat that I've seen before include "small weight" , "Measure of gold in alloy" , "Unit of weight for gems or purity of gold" , "weight of rocks" , "Precious stone weight" .)