Possible Clues:

• Whin
• Thorny plant becomes coated, they say
• Shrub
• Bushy growth providing warm covers for the ears
• Bush in which foxes, perhaps, can be heard
• Conifers recorded in gorse
• Sound coming from trees and gorse
• Shrub becomes coated, so they say
• Coats trees, say, and spiny shrub
• Prickly shrub an unethical form of covering, we're told