Closed Shop – 1. A place of work where you have to be in a union 2. An area of activity that is restricted to a particular small group

To remember the definition of the word closed shop, use the following mnemonic:

They closed the shop (closed shop) and wouldn't let anyone in without a union card.

Examples of closed shop in a sentence (place of work with union)

There was a closed shop policy in this company until a few years ago.

Although the closed shop is a feature of some unions, ours doesn't work like that.

I wouldn't want to work anywhere that has a closed shop policy. 

Examples of closed shop in a sentence (restricted area of activity)

After the game they wanted a drink in the players lounge but they were told it was a closed shop.

The warm-up arena of the dressage competition was a closed shop, only riders and trainers were allowed in.

A ballet dressing room following a performance is a closed shop, unwelcoming to outsiders.