Awful poster taken to the junction for the demo (7)
I believe the answer is:
protest
'demo' is the definition.
'awful poster taken to the junction for the' is the wordplay.
'awful' is an anagram indicator.
'taken to' says to put letters next to each other.
'the junction' says to put letters next to each other.
'for' says to put letters next to each other.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'poster' is an anagram of 'protes'.
'protes'+'t'='PROTEST'
(Other definitions for protest that I've seen before include "Record objection" , "Demonstrate" , "Express dissent" , "Object loudly" , "Complaint" .)