Spotted animal setter possibly observed on train (5,3)

'spotted animal' is the definition.
The answer and definition can be both animals as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'setter possibly observed on train' is the wordplay.
I cannot really see how this works, but
'setter' could be 'dog' (a setter is a type of dog) and 'dog' is present in the answer.
'train' could be 'coach' (synonyms) and 'coach' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?