Pet one worshipped rolling over (3)
I believe the answer is:
dog
'pet' is the definition.
(I know that dog is a type of pet)
'one worshipped rolling over' is the wordplay.
'one worshipped' becomes 'god' (I've seen this in another clue).
'rolling over' says the letters should be written backwards.
'god' reversed gives 'DOG'.
(Other definitions for dog that I've seen before include "Contemptible man" , "Domestic animal" , "plague?" , "A pet; its life prov. wretched" , "Domesticated canine" .)