A noted horse to urge on! (3)
I believe the answer is:
egg
This clue could be a double definition.
'a noted horse' is the first definition.
The definition and answer can be both animals as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'urge on' is the second definition.
'egg' can be an answer for 'urge' (as in egging someone on). I am unsure of the 'on' bit.
'to' is the link.
Can you help me to learn more?
(Other definitions for egg that I've seen before include "Good, boiled, yoke or head" , "Laid item" , "Hen fruit" , "Urge, ovum" , "One beaten by a whisker perhaps" .)