A Walton daughter (4)
I believe the answer is:
'a walton daughter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for erin that I've seen before include "Poetic name for Ireland" , "'Come back to ...' (emigrant song)" , "Let ... Remember (song)" , "Old Ireland" , "Ireland (poet.)" .)