Mile away from citrus (4)
I believe the answer is:
lime
'citrus' is the definition.
(lime is a kind of citrus)
'mile away' is the wordplay.
'away' indicates anagramming the letters (letters move away from their original places).
'mile' anagrammed gives 'LIME'.
'from' acts as a link.
(Other definitions for lime that I've seen before include "Another name for the linden tree" , "Sharp-tasting fruit" , "Having no money" , "Citrus fruit - shade of green" , "Acid green fruit like a lemon" .)