Trained dog to keep at home: not this one! (5)
I believe the answer is:
dingo
'home not this one' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'trained dog to keep at' is the wordplay.
'trained' indicates an anagram (train can mean to shape or manipulate).
'to keep' means one lot of letters goes inside another.
'at' becomes 'in' (synonymous in some cases - eg at school, in school).
'dog' anagrammed gives 'dgo'.
'dgo' enclosing 'in' is 'DINGO'.
Can you help me to learn more?
(Other definitions for dingo that I've seen before include "Kipling's "Yellow-Dog"" , "Australian native" , "Wild dog of Australia" , "Want a dog" , "Kipling's yellow dog" .)