Here’s a horse, your majesty (4)
I believe the answer is:
sire
'here's' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for sire that I've seen before include "Foal's father" , "Bear" , "Old form of address to king - rise to it" , "Stallion; beget" , "Male parent of a horse, for example" .)