Some crazes that will produce enthusiasm (4)
I believe the answer is:
zest
'enthusiasm' is the definition.
(zest can mean enthusiasm or eagerness)
'some crazes that will' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'ZEST' can be found hidden inside 'crazes that will'.
'produce' is the link.
(Other definitions for zest that I've seen before include "Keen excitement - citrus peel" , "taste" , "Enthusiasm - grated lemon peel" , "Orange or lemon peel" , "Orange-peel" .)