Crude apprentice, no longer in charge: He'll never grow up! (5,3)
I believe the answer is:
peter pan
'he'll never grow up' is the definition.
'crude apprentice no longer in charge' is the wordplay.
'crude' is an anagram indicator.
'no longer' is a deletion indicator.
'in charge' becomes 'ic'.
'apprentice' with 'ic' taken out is 'apprente'.
'apprente' with letters rearranged gives 'PETER PAN'.
(Other definitions for peter pan that I've seen before include "voyager to Never Never Land" , "Ever-young person" , "Pantomime hero" , ",one with youthful persona, maybe" , "ageless character" .)