For contracting, chooses the right book (6)
I believe the answer is:
esther
'book' is the definition.
(book of the Hebrew Bible)
'for contracting chooses the right' is the wordplay.
'for contracting' says the answer is hidden in the clue (the clue must be contracted or reduced).
'ESTHER' is hidden within 'chooses the right'.
(Other definitions for esther that I've seen before include "Fem. name, threes (anag.)" , "There's a girl from the Old Testament" , "There's the biblical woman" , "Set her with this girl" , "Now there's a lady" .)