Spokesperson's wickedness, admitting nothing (5)
I believe the answer is:
voice
'spokesperson's' is the definition.
(synonyms)
'wickedness admitting nothing' is the wordplay.
'wickedness' becomes 'vice' (I've seen this before).
'admitting' means one lot of letters goes inside another (admit can mean to welcome in or accept).
'nothing' becomes 'O' (looks like zero - 0).
'vice' enclosing 'o' is 'VOICE'.
(Other definitions for voice that I've seen before include "Articulate" , "Speak of - mouthpiece" , "tenor, say" , "Articulation, speech" , "Sound of speaker" .)