Some joker educating backward boy (5)
I believe the answer is:
derek
'boy' is the definition.
'some joker educating backward' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'backward' says the letters should be written backwards.
'kered' can be found hidden inside 'joker educating'.
'kered' written backwards gives 'DEREK'.
(Other definitions for derek that I've seen before include "Man's name" , "Fellow" , "- and the Dominos was Eric Clapton's band" , "Sir - - Jacobi (actor)" .)