Eastern bread — you must bin old one (4)
I believe the answer is:
yuan
'one' is the definition.
The definition and answer can be both quantities as well as being singular nouns.
Maybe you can see a link between them that I don't see?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for yuan that I've seen before include "Income in Shanghai" , "Chinese monetary unit" , "Monetary unit of China" , "money abroad" , "foreign currency" .)