Wicked? Yes, with no love lost (3)
I believe the answer is:
sin
'wicked? yes with no love lost' is the definition.
I can't tell whether this definition defines the answer.
'yes with no love lost' is the wordplay.
'yes with' becomes 'si' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'love' becomes 'o' (In tennis, 'love' means 'zero').
'lost' suggests deleting specific letters.
'no' with 'o' taken away is 'n'.
'si'+'n'='SIN'
Can you help me to learn more?
(Other definitions for sin that I've seen before include "'Transgression, mortal or venial (3)'" , "Serious transgression" , "Breach of morality" , "Err" , "Misdeed" .)