The answer to the clues below will have something in common.

1. Over-protective one

2. Symbolic American

3. He's always watching

4. Vague relation 

5. Tart green apple 

6. Pittsburgh, PA and Sheffield, England  

7. The guard in The Wizard of Oz had one

8. Wording recognizing previous rights and exempting certain people or things from the requirements of new legislation

 

Answers:

 

1. Mother hen

2. Uncle Sam

3. Big Brother

4. Distant cousin

5. Granny Smith

6. Sister cities

7. Aunt Em

8. Grandfather clause