Bean say eaten by crazy mule (6)
I believe the answer is:
legume
'bean' is the definition.
(thesaurus)
'say eaten by crazy mule' is the wordplay.
'say' becomes 'eg'.
'eaten by' is an insertion indicator.
'crazy' is an anagram indicator.
'mule' anagrammed gives 'lume'.
'eg' going into 'lume' is 'LEGUME'.
(Other definitions for legume that I've seen before include "A vegetable for e.g. mule" , "Pea, bean or lentil?" , "Vegetable of pea family" , "A plant of the kind that bears its seeds in pods" , "Veg as pea, bean" .)