Scarecrow's wish in "The Wizard of Oz" (5)
I believe the answer is:
brain
'scarecrow's wish in the wizard of oz' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for brain that I've seen before include "Intellectual capacity" , "Clever type" , "Encephalon" , "Clever person" , "Intelligence" .)