Sick bird sounded wrong (7)
I believe the answer is:
illegal
'wrong' is the definition.
(I've seen this before)
'sick bird' is the wordplay.
'sick' becomes 'ill' (synonyms).
'bird' becomes 'egal' (I can't justify this - if you can you should believe this answer much more).
'ill'+'egal'='ILLEGAL'
'sounded' is the link.
This may not be correct. It may be part of another bit of the clue.
(Other definitions for illegal that I've seen before include "Not allowed" , "Not in conformity with law" , "Prohibited by law" , "murder sure is!" , "Unlawful" .)