Favourites about to show pace (4)
I believe the answer is:
step
'pace' is the definition.
(I know that pace can be written as step)
'favourites about' is the wordplay.
'favourites' becomes 'pets' ('pet' can be a synonym of 'favourite').
'about' says the letters should be written backwards.
'pets' backwards is 'STEP'.
'to show' is the link.
(Other definitions for step that I've seen before include "Measure - pace" , "Gradation" , "Footprint" , "Foot movement" , "Stage - pace" .)