Youngest March sister (3)
I believe the answer is:
amy
'youngest march sister' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for amy that I've seen before include "so-called little woman" , "Girl" , "--, Johnson, solo flyer" , "Youngest of Little Women" , "Girl's name; 3 dn (anag.)" .)