A backward boy (3)
I believe the answer is:
yob
'a backward boy' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'backward boy' is the wordplay.
'backward' shows that the letters should be reversed in order.
'boy' written backwards gives 'YOB'.
Can you help me to learn more?
(Other definitions for yob that I've seen before include "Lout (sl.)" , "Lout or hooligan, backward boy" , "Loutish young man" , "Thug" , "Hooligan kind of boy" .)