To many a boy, an assertive little girl (5)
I believe the answer is:
madam
'an assertive little girl' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'to many a boy' is the wordplay.
'to many' becomes 'm'.
'a boy' becomes 'adam' ().
'm'+'adam'='MADAM'
Can you help me to learn more?
(Other definitions for madam that I've seen before include "Woman of standing" , "Formal address to a woman - precocious little girl" , "formidable woman" , "How one may address a woman" , "Woman running a brothel" .)