Harsh, strict (6)
I believe the answer is:
severe
This clue is a double definition.
'harsh' is the first definition.
(I've seen this before)
'strict' is the second definition.
(I've seen this before)
(Other definitions for severe that I've seen before include "Harsh and stringent" , "Harsh - extreme" , "Formal - unsmiling" , "Critical" , "Harsh, rigorous" .)