There's a change in the Old Testament (6)
I believe the answer is:
esther
'the old testament' is the definition.
Both the definition and answer are singular nouns.
I also know that 'old testament' relates to this answer.
'there's a change' is the wordplay.
'a change' indicates an anagram.
'theres' anagrammed gives 'ESTHER'.
'in' is the link.
Can you help me to learn more?
(Other definitions for esther that I've seen before include "There's the biblical woman" , "Old Testament book that tells of a beautiful Jewess" , "There's a girl from the Old Testament" , "OT heroine" , "Old Testament book telling of a beautiful Jewess" .)