Across

1. Horned and bearded animal

3. Cook by boiling slowly

6. Mathematics

9. An assistant

11. Not the beginning

12. Fur loving pest

13. Too

14. Tear

15. Do this to a fly

17. Hammer or wrench

20. Unwanted lawn growth

21. Not fast

Down

1. Precious stone

2. Small insect

4. Prefix meaning 3

5. Grief, misery

7. Permit

8. It pumps blood

9. Alter to be suitable

10. 70’s style of music

15. Stitch with needle and thread

16. Number of years old

18. Hooting bird

19. Not high