The following clues lead to six and five letter answers respectively. The answer to the second clue is the first clue answer minus one letter with no anagramming necessary. Each letter of the alphabet is represented only once with the exception of "Q" because I couldn't come up with one.
Identify the two words and the letter of the alphabet that applies.
Example: floor covering > insertion point mark = carpet > caret (P)
A C O S
-1. a mineral > a measurement
-2. band of tissue > type of wood joint3.
-3. barrister > tier
-4. bends > runs off
-5. buccaneer > blab
-6. clown > acid + alcohol product
-7. deprive of food > ogle
-8. detachable shirt collar > unpredictable
-9. expression > stage
-10. fireplace > soil
-11. flub > musical instrument
-12. healthy > stimulate
-13. outside cooling device > cheapskate
-14. part of the skeletal system > The King
-15. person's possessions > condition
-16. plan of study > swear
-17. province > body part
-18. provision in a document > precipitate
-19. quantity > escalate
-20. shaving > an organ
-21. slant > pole used in Scottish sport
-22. span > word with groom or war
-23. sponsor > chef
-24. stumble > change
-25. tap > aspect