Vilify me in a sarcastic piece (5)
I believe the answer is:
smear
'vilify' is the definition.
(I've seen this in another clue)
'me in a sarcastic piece' is the wordplay.
'in' indicates putting letters inside.
'a sarcastic piece' becomes 'sar' (I can't justify this - if you can you should give a lot more credence to this answer).
'me' going into 'sar' is 'SMEAR'.
Can you help me to learn more?
(Other definitions for smear that I've seen before include "Slander - tissue sample used for testing" , "Blur, smudge" , "sample on slide" , "Smother" , "material for examination that is on the slide" .)