Domestic animals pace backwards (4)
I believe the answer is:
pets
'domestic animals' is the definition.
(animals in the home)
'pace backwards' is the wordplay.
'pace' becomes 'step' (synonyms).
'backwards' says the letters should be written backwards.
'step' in reverse letter order is 'PETS'.
(Other definitions for pets that I've seen before include "Domesticated animals" , "Animals at home" , "Little darlings - step on them" , "Domestic animals" .)