Harsh adjustment to net ratings (10)
I believe the answer is:
astringent
'harsh' is the definition.
(thesaurus)
'adjustment to net ratings' is the wordplay.
'adjustment to' is an anagram indicator.
'net'+'ratings'='netratings'
'netratings' anagrammed gives 'ASTRINGENT'.
(Other definitions for astringent that I've seen before include "for checking bleeding" , "Sharp or severe in manner" , "medical preparation" , "acerbic" , "Caustic" .)