Break china overturned after cold rhubarb (8)
I believe the answer is:
claptrap
'rhubarb' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'break china overturned after cold' is the wordplay.
'break' becomes 'part' ().
'china' becomes 'pal' (china plate is Cockney rhyming slang for mate).
'overturned' is a reversal indicator.
'after' is a charade indicator (letters next to each other).
'cold' becomes 'C' (eg on taps).
'part'+'pal'='partpal'
'partpal' back-to-front is 'laptrap'.
'laptrap' put after 'c' is 'CLAPTRAP'.
Can you help me to learn more?
(Other definitions for claptrap that I've seen before include "Contrived but foolish talk" , "Bull" , "Empty words" , "Meaningless, insincere or pompous talk" , "poppycock" .)