Nellie is entertained by the fellow who comes from Greece? (7)
I believe the answer is:
hellene
'who comes from greece?' is the definition.
(Hellenes can mean the Ancient Greeks)
'nellie is entertained by the fellow' is the wordplay.
'nellie' becomes 'Ellen' (Nellie can be short for Ellen).
'is entertained by' indicates putting letters inside (entertain can mean to host or welcome in).
'the fellow' becomes 'he' (pronoun for a man).
'ellen' put within 'he' is 'HELLENE'.
(Other definitions for hellene that I've seen before include "Greek girl" , "old Greek" .)