Subtle punishment (4)
I believe the answer is:
fine
I believe this is a double definition.
'subtle' is the first definition.
('fine' can be a synonym of 'subtle')
'punishment' is the second definition.
(fine is a kind of punishment)
(Other definitions for fine that I've seen before include "Excellent - form of punishment" , "No special brandy" , "Not coarse" , "French brandy" , "Magnificent" .)