The answers to the following clues contain three of the same letter from the list shown somewhere within the word.
Example: b
An
An
AD
-1. abnormal (7)
-2. sewing machine component (6)
-3. accentuate with color (9)
-4. "
Daddy's Father's Little __________ " (8)
-5. a quantity computed from a sample (9)
-6. it could be first, third or a master's (6)
-7. word with car or excess (7)
-8. poster for theater performance (8)
-9. company (8)
-10. devise (7)
-11. 2009 James Cameron movie (6)
-12. botch or down (5)
-13. hinder (7)
-14. a strong or violent reaction (8)
-15. escape clause (8)
-16. the Yankees won it in 2009 (7)
-17. usurp (11)
-18. water supply (9)
-19. most (7)
-20. informal meeting (6)