Some backing from fair American girl (5)
I believe the answer is:
maria
'girl' is the definition.
'some backing from fair american' is the wordplay.
'some backing' shows that the letters should be reversed in order.
'from' says the answer is hidden in the clue.
'airam' is hidden in the letters of 'fair american'.
'airam' backwards is 'MARIA'.
(Other definitions for maria that I've seen before include "Lady" , "Lunar plains; girl's name" , "Black --, -- Theresa" , "- Callas, twentieth century opera singer" , "Von Trapp star" .)