Loss of confidence in fresh feed consumed by horse (4,4)
I believe the answer is:
cold feet
'loss of confidence' is the definition.
(getting cold feet means getting doubtful)
'fresh feed consumed by horse' is the wordplay.
'fresh' is an anagram indicator.
'consumed by' means one lot of letters goes inside another (inserted letters get consumed).
'horse' becomes 'colt' (I've seen this before).
'feed' with letters rearranged gives 'dfee'.
'dfee' placed inside 'colt' is 'COLD FEET'.
'in' is the link.
(Other definitions for cold feet that I've seen before include "Lack of courage or confidence" , "Chilly extremities due to fear" , "You might have them if you're afraid to proceed" , "Loss of courage or confidence" , "Apprehension" .)