Action favourites return (4)
I believe the answer is:
step
'action' is the definition.
(step is a kind of action)
'favourites return' is the wordplay.
'favourites' becomes 'pets' ('pet' can be a synonym of 'favourite').
'return' says the letters should be written backwards.
'pets' back-to-front is 'STEP'.
(Other definitions for step that I've seen before include "Prefix meaning related by remarriage" , "Set foot down on pest" , "Move a little way" , "Pace - part of a procedure" , "Section of flight" .)