Draconian backside! (5)
I believe the answer is:
stern
I believe this is a double definition.
'draconian' is the first definition.
(I've seen this in another clue)
'backside' is the second definition.
(I know that backside can be written as stern)
(Other definitions for stern that I've seen before include "Unyielding - rump" , "Rear end" , "Unpleasantly serious" , "Strict, grimly serious" , "End part" .)