In such a town there is no equestrian competition (3,5)
I believe the answer is:
one horse
'in' is the definition.
Both the answer and definition are adjectives. Perhaps they are linked in a way I don't understand?
'a town there is no equestrian competition' is the wordplay.
I cannot really understand how this works, but
'a' could be 'one' and 'one' is found in the answer.
'no' could be 'o' (O resembles 0) and 'o' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'such' is the link.
Can you help me to learn more?
(Other definitions for one horse that I've seen before include "like some carriages?" , "Minor" , "mean" , "small and unimportant" , "Like town with > inadequate resources" .)