Union arrangement ended quiet operation (6,4)
I believe the answer is:
closed shop
'union arrangement' is the definition.
The definition and answer can be both groups as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'ended quiet operation' is the wordplay.
'ended' becomes 'closed' (closing is a kind of ending).
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'operation' becomes 'op'.
'closed'+'sh'+'op'='CLOSED SHOP'
Can you help me to learn more?
(Other definitions for closed shop that I've seen before include "factory where all the workers are unionists" , "firm with restrictive hiring policy" , "Where union membership is required" , "Ceased trading" , "Union bastion" .)