Discussed decline in protest (7)
I believe the answer is:
dissent
'protest' is the definition.
(I know that protest can be written as dissent)
'discussed decline' is the wordplay.
'discussed' shows a homophone (sound like).
'decline' becomes 'descent' (synonyms).
'descent' sounds like 'DISSENT'.
'in' acts as a link.
(Other definitions for dissent that I've seen before include "Disagree" , "Objection" , "Protest" , "Open disagreement" , "Express a different opinion" .)