Mother of Jesus (4)
'mother of jesus' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mary that I've seen before include "Sinner who became a follower of Jesus" , "O'Rourke, Harney and McAleese" , "Successor to Edward VI" , "could be Wesley" , "feature of 21/23 [NATIVITY SCENE]" .)