A plain Jane (4)
I believe the answer is:
eyre
'a plain jane' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eyre that I've seen before include "heroine, so-called" , "SECOND PART OF 20" , "See 1" , "one loved by Rochester" , "C. Bronte's orphan Jane" .)