Follow best friend (3)
I believe the answer is:
dog
This might be a double definition.
'follow' is the first definition.
(dog can mean to follow or torment)
'best friend' is the second definition.
The answer and definition can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for dog that I've seen before include "Hound" , "'You cannot teach an old ... new tricks'" , "'Every . . . has its day'" , "Follow; pet" , "Worry" .)