The answers to the clues below contain abbreviations.

1. Iconic blues singer of Goodnight Irene
2. The "May" in some May-December marriages
3. Tonto portrayer
4. Hair color
5. Early theater
6. Railroad - to some
7. Environmental impact
8. Breathing support
9. Balloon filler upper at a party, perhaps

Answers:

1. Pb Belly
2. Au digger
3. Ag Heels
4. Pt blonde
5. Ni odeon
6. Fe Horse
7. C footprint
8. O tent
9. He tank

Credit:
NY Times Crossword
July 23, 1998 
Randall J. Hartman

Explanation of answer abbreviations:

Each abbreviation is the chemical symbol of an element:

1. Lead Belly
2. Gold digger 
3. Jay Silverheels
4. Platinum blonde
5. Nickelodeon
6. Iron horse 
7. Carbon footprint
8. Oxygen tent
9. Helium tank