Harsh treatment regimen given orally (6)
I believe the answer is:
coarse
'harsh' is the definition.
(thesaurus)
'treatment regimen given orally' is the wordplay.
'treatment regimen' becomes 'course' (eg a course of medication).
'given orally' shows a homophone (sound like).
'course' is a homophone of 'COARSE'.
(Other definitions for coarse that I've seen before include "Rough, harsh" , "Rough to the touch or lacking refinement" , "Large-grained or rough to the touch" , "Rude, vulgar" , "Rude, base" .)