Favourites about to show pace (4)
I believe the answer is:
step
'pace' is the definition.
(synonyms)
'favourites about' is the wordplay.
'favourites' becomes 'pets' ('pet' can be a synonym of 'favourite').
'about' shows that the letters should be reversed in order.
'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" .)