To do wrong to a good end, seems strange (3)
I believe the answer is:
odd
'strange' is the definition.
(I've seen this before)
'to do wrong to a good end' is the wordplay.
'wrong' indicates an anagram.
'to a good end' becomes 'd' (I can't explain this - if you can you should believe this answer much more).
'do' with letters rearranged gives 'od'.
'od'+'d'='ODD'
'seems' is the link.
Can you help me to learn more?
(Other definitions for odd that I've seen before include "Funny" , "like twenty two [FIFTEEN]? Yes and no!" , "It's certainly not even" , "Unusual, strange" , "Freakish" .)