Domestic animals backing part of procedure (4)
I believe the answer is:
step
'procedure' is the definition.
(I've seen this in another clue)
'domestic animals backing' is the wordplay.
'domestic animals' becomes 'pets' (animals in the home).
'backing' shows that the letters should be reversed in order.
'pets' in reverse letter order is 'STEP'.
'part of' acts as a link.
(Other definitions for step that I've seen before include "Bit of mashed potato maybe" , "Pest (anag.)" , "Foot movement" , "Tread - stage" , "Footprint" .)