From Longman Dictionary of Contemporary Englishclosed shopˌclosed ˈshop noun [countable] BELa company, factory etc where all the workers must belong to a particular trade union
Examples from the Corpus
closed shop• This was not so easy at that time as the crewing arrangements were very much of a closed shop.• Herein lies the crucial difference between open shop and closed shop monopoly union models.• The production unions' success had various causes, including an effective closed shop and weak newspaper managements.• It was the last closed shop in Britain, he said, and it had to go.• Tebbit found himself unable to outlaw the closed shop entirely.From Longman Business Dictionaryclosed shopˌclosed ˈshop noun [countable usually singular]1HUMAN RESOURCES a place of work where only members of a particular TRADE UNION are employedMr Blair was criticised by union leaders when he dropped his support of the closed shop.2COMMERCE a market or organization where people from outside it are not allowed 