Cain's victim (3)
'cain's victim' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for abel that I've seen before include "Cain's 11" , "Bale out with murder victim" , "The first murderee?" , "Early man equipped" , "Adamson" .)
(Other definitions for abe that I've seen before include "Lincoln, familiarly" , "Eg, president Lincoln" , "President Lincoln was known as Honest ..." , "Lincoln's diminutive" .)