Main character is present, having nothing at home (7)
I believe the answer is:
heroine
'main character' is the definition.
(main character in a story)
'present having nothing at home' is the wordplay.
'present' becomes 'here' (both can mean in attendance).
'having' means one lot of letters goes inside another.
'nothing' becomes 'O' (looks like zero - 0).
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'o'+'in'='oin'
'here' going around 'oin' is 'HEROINE'.
'is' is the link.
(Other definitions for heroine that I've seen before include "Chief female character in a book" , "Intrepid woman" , "Leading lady" , "Perhaps Tess" , "Eg, Emma, Jane Eyre" .)