Craze over Portuguese song (4)
I believe the answer is:
fado
'portuguese song' is the definition.
(type of song in Portugal)
'craze over' is the wordplay.
'craze' becomes 'fad' (synonyms).
'over' becomes 'o' (cricket abbreviation).
'fad'+'o'='FADO'
(Other definitions for fado that I've seen before include "Portuguese folk song" , "Portuguese song genre" , "Melancholy style of song popular in Portugal" , "Portuguese traditional dance and doleful song" , "Portuguese song style" .)