Evil welcoming love's expression (5)
I believe the answer is:
voice
'expression' is the definition.
(voice is a kind of expression)
'evil welcoming love's' is the wordplay.
'evil' becomes 'vice' (vice is a kind of evil).
'welcoming' means one lot of letters goes inside another (in sense of 'inviting in').
'love' becomes 'o' (In tennis, 'love' means 'zero').
'vice' enclosing 'o' is 'VOICE'.
(Other definitions for voice that I've seen before include "tenor, say" , "Opinion; express in words" , "Sound produced by humans" , "right to have a say" , "Ability to speak, sing" .)