Aunt Sally's happy family? (8,5)
I believe the answer is:
laughing stock
'aunt sally's' is the definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I can't see?
'happy family?' is the wordplay.
'happy' becomes 'laughing' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'family?' becomes 'stock' (family is a kind of stock).
'laughing'+'stock'='LAUGHING-STOCK'
Can you help me to learn more?
(Other definitions for laughing stock that I've seen before include "Butt of ridicule" , "Object to joke" , "Target of ridicule" , "inhabitants of funny farm?" , "Object of ridicule" .)