A boy's name or a girl's name (7)
I believe the answer is:
leonora
'girl's name' is the definition.
'a boy's name or a' is the wordplay.
'a boy' becomes 'leo' (boy's name).
'name' becomes 'n' (common abbreviation e.g. on forms).
'leo'+'n'+'or'+'a'='LEONORA'
(Other definitions for leonora that I've seen before include "Girl" , "Name of woman" , "Girl's name; or alone (anag.)" , "Heroine of Beethoven's Fidelio" .)