Old Testament queen (6)
I believe the answer is:
esther
'old testament queen' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for esther that I've seen before include "Now there's a lady" , "religious book" , "Girl's name; OT book" , "__ Rantzen, TV presenter, b. 1940" , "Oratorio by Handel; girl's name" .)