Nervous horse, perhaps

• Silver, for example, in the opening to TV's "The Lone Ranger"
• Mom or dad, traditionally
• Skittish steed
• Terrified horse, at times
• Parent or scared horse
• Parent, for example
• One bringing up children behind the Queen

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Rearer \Rear"er\ (r[=e]r"[~e]r), n. One who, or that which, rears.

Wiktionary Word definitions in Wiktionary
n. 1 One who rear#Verb (gloss: nurtures children or animals). 2 A horse or other animal that rears up.