Adam and Eve’s second son (4)
I believe the answer is:
abel
'adam and eve's second son' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for abel that I've seen before include "Cain slew him" , "Early murder victim" , "The first recorded murder victim" , "Bale out with murder victim" , "One of the first children" .)