Fellow in something like Prodigal Son story not beyond redemption (10)
I believe the answer is:
pardonable
'not beyond redemption' is the definition.
(able to be pardoned or redeemed)
'fellow in something like prodigal son story' is the wordplay.
'fellow' becomes 'don' (both can mean an academic).
'in' means one lot of letters goes inside another.
'something like prodigal son story' becomes 'parable' (the prodigal son story is a biblical parable).
'don' inserted within 'parable' is 'PARDONABLE'.
(Other definitions for pardonable that I've seen before include "likely to go unpunished?" , "Capable of being forgiven" , "Excusable" , "not too serious?" , "venial" .)