As far as “a dud on evil bent” (2,2,2,4)
I believe the answer is:
up to no good
'evil bent' is the definition.
I know nothing about this answer so I can't tell whether this works.
'as far as a dud' is the wordplay.
'as far as' becomes 'upto' (I've seen this before).
'a dud' becomes 'nogood' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'upto'+'nogood'='UP TO NO GOOD'
'on' acts as a link.
Can you help me to learn more?
(Other definitions for up to no good that I've seen before include "Scheming to do wrong(2.2.2.4)" , "Doing something mischievous" , "Making mischief" , "Doing something wrong" , "Misbehaving" .)