In which cases we can use shop with indefinite article ? Usually it is used with definite one
I go to the shop everyday.
Is it possible to say : I bought it in a shop.
Or : She works in shop.
She works in a shop.

Question

In which cases  we can use shop  with  indefinite article ? Usually it is used  with definite one
I  go to  the shop  everyday. 
Is it possible to say :  I  bought  it  in a shop.
Or :  She works  in  shop.    
        She works in a shop.

Answer

"I bought it in a shop" is good and "She works in a shop" is correct