Wicked Bard has sent up Liberal (4)
I believe the answer is:
evil
'wicked' is the definition.
(similar in meaning)
'bard has sent up liberal' is the wordplay.
'bard has' becomes 'ive' (I can't explain this - if you can you should give a lot more credence to this answer).
'sent up' says the letters should be written in reverse.
'liberal' becomes 'l' (abbreviation).
'ive' backwards is 'evi'.
'evi'+'l'='EVIL'
Can you help me to learn more?
(Other definitions for evil that I've seen before include "Immorality" , "Morally objectionable behavior" , "Extremely unpleasant" , "Excellent" , "source of harm" .)