Stage in which favourites turned up (4)
I believe the answer is:
step
'stage' is the definition.
(as in a step or stage of a process)
'favourites turned up' is the wordplay.
'favourites' becomes 'pets' ('pet' can be a synonym of 'favourite').
'turned up' shows that the letters should be reversed in order.
'pets' in reverse letter order is 'STEP'.
'in which' acts as a link.
(Other definitions for step that I've seen before include "Manner of walking" , "Prefix meaning related by remarriage" , "Football" , "Single pace" , "Section of flight" .)