Possible Clues:

• Blacksmith's creation
• Iron plate beneath a hoof
• Steed's footwear features Avenger's extremity in two forms of hose
• Charm of Arab, say, at Oxford?
• Plate nailed to equine hoof
• Supposedly lucky piece of metal
• It can spread and cause a delay
• Hack is shown over Oxford, possibly? Lucky thing
• Good luck bringer?
• Shore hose (anag.)