Compulsory union membership policy forced store to cease trading (6,4)
I believe the answer is:
closed shop
'compulsory union membership' is the definition.
The answer and definition can be both groups as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'policy forced store to cease trading' is the wordplay.
I cannot really see how this works, but
'store' could be 'shop' (synonyms) and 'shop' is found within the answer.
'to' could be 'closed' (I've seen this before) and 'closed' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for closed shop that I've seen before include "Where union membership is required" , "Shut down business" , "Union bastion" , "Exclusive workers" , "Ceased trading" .)