Crazes (4)
'crazes' is the definition.
('fad' can be a synonym of 'craze')
This is all the clue.
(Other definitions for fads that I've seen before include "Short-lived crazes" , "Fashions or vogues" .)
(Other definitions for trends that I've seen before include "Inclinations or fashions" , "Current movements, in fashion say" , "Fashion directions or continuing tendencies" , "current fashions" , "Current movements in styles, tastes etc." .)