Follow the pet (3)
I believe the answer is:
dog
I believe this is a double definition.
'follow' is the first definition.
(dog can mean to follow or torment)
'pet' is the second definition.
(I know that dog is a type of pet)
'the' acts as a link.
(Other definitions for dog that I've seen before include "'You cannot teach an old ... new tricks'" , "A pet; its life prov. wretched" , "plague?" , "Hound" , "Follow - canine" .)