Each of the words below can be changed into a common two-word phrase by adding a second word beginning with the same two letters as the first word, only reversed.

1. New
2. Car
3. Arms
4. Walk
5. Usual
6. Mirror
7. Ninth
8. Opium
9. Foreign
10. National
11. Unlisted

Answer:

1. New England 
2. Car accident
3. Arms race
4. Walk away
5. Usual suspects
6. Mirror image
7. Ninth inning
8. Opium poppy
9. Foreign office
10. National anthem
11. Unlisted number  

Credit:
Will Shortz
The Puzzlemaster Presents Vol. 2
STARTER SWITCH