What a hound may do for a horse (3)
I believe the answer is:
bay
'horse' is the definition.
(I know that bay is a type of horse)
'what a hound may do' is the wordplay.
I cannot quite understand how this works, but
'a' is found in the answer.
The remaining letters 'by' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'for a' acts as a link.
Can you help me to learn more?
(Other definitions for bay that I've seen before include "Indentation of a shoreline" , "Botany, Galway or Tampa" , "Laurel tree - bark" , "Tree; horse; bark loudly" , "Inlet, cove" .)