Authorise punishment (8)
I believe the answer is:
sanction
I believe this clue is a double definition.
'authorise' is the first definition.
(I know that sanction is a more specific form of the action authorise)
'punishment' is the second definition.
(I've seen this before)
(Other definitions for sanction that I've seen before include "Give approval to, authorise" , "Official permission or authority" , "OK" , "coercive measure" , "measure taken against offending country?" .)