Rating turned colour of ash, reportedly (5)
I believe the answer is:
grade
'rating' is the definition.
(grade is a kind of rating)
'turned colour of ash reportedly' is the wordplay.
'turned colour of ash' becomes 'greyed'.
'reportedly' shows a homophone (sound like).
'greyed' is a homophone of 'GRADE'.
(Other definitions for grade that I've seen before include "Particular level of rank, quality, etc" , "Rank or status" , "Degree" , "one of the entertainment moguls" , "School mark" .)