Sadie gets wrong thoughts (5)
I believe the answer is:
ideas
'thoughts' is the definition.
(I know this)
'sadie gets wrong' is the wordplay.
'gets wrong' indicates anagramming the letters (I've seen 'got wrong' mean this).
'sadie' with letters rearranged gives 'IDEAS'.
(Other definitions for ideas that I've seen before include "Thoughts, creative perhaps" , "Brainwaves" , "Thoughts or opinions" , "Thoughts, perceptions" , "Notions, thoughts" .)