Food a mile off (4)
I believe the answer is:
lime
'food' is the definition.
(lime is a kind of food)
'a mile off' is the wordplay.
'off' indicates anagramming the letters.
'mile' with letters rearranged gives 'LIME'.
(Other definitions for lime that I've seen before include "Mailed item" , "Kind of tree or substance used in cement" , "Tree, linden or citrus" , "white caustic earth" , "Green fruit -- green colour" .)