Something wicked about 'Nothing to declare'? (5)
I believe the answer is:
voice
'declare'?' is the definition.
(I've seen this in another clue)
'something wicked about 'nothing' is the wordplay.
'something wicked' becomes 'vice' (a vice is wicked or sinful).
'about' is an insertion indicator.
''nothing' becomes 'O' (looks like zero - 0).
'vice' placed around 'o' is 'VOICE'.
'to' acts as a link.
(Other definitions for voice that I've seen before include "Spokesperson" , "tenor, say" , "Opinion; part in a fugue" , "Power of speech" , "Articulation, speech" .)