There's a change in this girl (6)
I believe the answer is:
esther
'this girl' is the definition.
'there's a change' is the wordplay.
'a change' is an anagram indicator.
'theres' anagrammed gives 'ESTHER'.
'in' is the link.
(Other definitions for esther that I've seen before include "Old Testament book that tells of a beautiful Jewess" , "Oratorio by Handel; girl's name" , "There's a biblical girl" , "Old Testament book telling of a beautiful Jewess" , "OT heroine" .)