Possible Clues:

• That's not a firm, French one for a horse
• Not still with the horse in at last
• International authority on racehorses is not reliable
• Wobbly, lacking capacity to cross public way
• For the horse, a French one is not so firm
• Volatile, precarious
• Prone to change
• There's a horse there at last that makes it not so steady
• Not a steady one for the horse at last
• If the horse is not steady, get it out, perhaps