COUNT ON IT I

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

1. Can't stop thinking about the same thing
2. He just can't win
3. What may happen if you don't shave
4. Radcliffe, Smith, Vassar, etc.
5. Clio, Calliope, Terpsichore, etc.
6. Just before it's too late
7. USA before there was a USA
8. Andy Warhol's allotment to each of us
9. Long-lasting teen magazine
10. Country club feature
11. It's a winner in Las Vegas
12. His and hers make up Junior
13. It's silver

Answers:

1. One-track mind
2. Three-time loser
3. Five o'clock shadow
4. Seven Sisters
5. Nine Greek Muses
6. Eleventh hour
7. Thirteen Colonies
8. Fifteen minutes of fame
9. Seventeen 
10. Nineteenth Hole
11. Twenty-one in Black Jack
12. Twenty-three chromosomes
13. Twenty-fifth wedding anniversary

Credit: LA Times Crossword
Sylvia Bursztyn and Barry Tunick
THAT'S ODD  (adapted)