Changed as to fodder (4)
I believe the answer is:
oats
'fodder' is the definition.
(I've seen this in another clue)
'changed as to' is the wordplay.
'changed' indicates an anagram.
'as'+'to'='asto'
'asto' with letters rearranged gives 'OATS'.
(Other definitions for oats that I've seen before include "Sow wild ones in disreputable youth" , "Cereal plants" , "Hardy cereals eaten by horses" , "Basis of porridge" , "Seed grasses" .)