Amazing change in Lauren (6)
I believe the answer is:
unreal
'amazing' is the definition.
(unreal can informally mean amazing or incredible)
'change in lauren' is the wordplay.
'change in' indicates anagramming the letters.
'lauren' is an anagram of 'UNREAL'.
(Other definitions for unreal that I've seen before include "Not true to life" , "Existing only in the imagination, not actual" , "Illusory; amazing" , "Not factual" , "Dreamlike" .)