Backing the favourites to show some pace (4)
I believe the answer is:
step
'some pace' is the definition.
(synonyms)
'backing the favourites' is the wordplay.
'backing' shows that the letters should be reversed in order.
'the favourites' becomes 'pets' ('pet' can be a synonym of 'favourite').
'pets' backwards is 'STEP'.
'to show' is the link.
(Other definitions for step that I've seen before include "Footprint" , "short distance" , "Place foot on as with a pest" , "Measure taken" , "Part of a stairway" .)