Previous cryptic solution

Across: 1. Class 4. Flaccid 8. Fortification 10. Canoe 11. Mode 12. Dish 16. Idiom 17. Imperceptible 19. Earnest 20. Surge

Down: 1. Coffee machine 2. Air 3. Switch 4. Feigns 5. Amazed 6. Criticism 7. Dental hygiene 9. Red pepper 13. Fierce 14. Silent 15. Smiths 18. Bar