Bait and switch: Each clue below can be answered by changing one letter in the given, capitalized word, and then anagramming the letters. Some easy, some alterative spellings, some Brit-words, and a few that may need the Stitchionary. Plenty to go round, so feel free to grab a couple.
-1. Part of the eye
-2. Scottish mathematician
-3. Person of noble birth
-4. Retract (usually a statement)
-5. Mysterious, esoteric
-6. Tip, sway, lean to one side whilst in motion
-7. Horticultural saccharine secretion
-8. Armed cavalryman
-9. Unit of distance required to cause a heliocentric parallax of one second of an arc
-10. Military policeman
-11. Exhort, usually in a religious manner
-12. Savoury titbit Lose the "R" and give the "E" an acute accent...
-13. Three-beat collected gait of a horse
-14. Member state of the E.U.
-15. Disease of horses in which the horn of the hoofs becomes soft and spongy
-16. Hypnotic state
-17. Armoured tank
-18. Carried away, ecstatic Lose the "C" and gain a letter towards the end of the alphanet...
-19. Tax evader
-20. Soft furnishing
-21. Lined with mother-of-pearl
-23. Hand tool consisting of a compound lever for grasping
-24. Tricky situation or predicament
-25. Friendly cartoon character
-26. Small package
-27. Large underground chamber
-28. Bizet opera
-29. Small RV
You know what I did before I married Mrs Worrier? Anything I wanted to.