Yes, boy, he's a classic hero (5)
I believe the answer is:
jason
I believe this clue is a quadruple definition!!
'yes boy' is the first definition.
'jason' can be an answer for 'boy' (I've seen this before). I'm not certain of the 'yes' bit.
'he's' is the second definition.
(I've seen this before)
'a classic' is the third definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'hero' is the fourth definition.
(I've seen this before)
Can you help me to learn more?
(Other definitions for jason that I've seen before include "He sought the Golden Fleece" , "He led the Argonauts to find the Golden Fleece" , "He sailed in search of the Golden Fleece" , "Greek hero, captain of the Argo" , "He sailed the Argo to find the Golden Fleece" .)