Craze to wane shortly (3)
I believe the answer is:
fad
'craze' is the definition.
(I know that craze can be written as fad)
'wane shortly' is the wordplay.
'wane' becomes 'fade' (I've seen this in another clue).
'shortly' means to remove the last letter.
'fade' with its last letter removed is 'FAD'.
'to' acts as a link.
(Other definitions for fad that I've seen before include "Caprice" , "A passing liking or fashion" , "Temporary vogue or craze" , "Passionate interest" , "'Craze, all the rage (3)'" .)