Horse and cattle fodder adapted to season (6)
I believe the answer is:
forage
'horse and cattle fodder' is the definition.
(food given to animals)
'adapted to season' is the wordplay.
'adapted to' becomes 'for' (something is adapted to whatever it is for).
'season' becomes 'age' (season can mean a period or age).
'for'+'age'='FORAGE'
(Other definitions for forage that I've seen before include "look around" , "Seek for food" , "Rummage, go searching" , "Rummage, search for" , "Collect food" .)