Full agreement, we hear (6)
I believe the answer is:
packed
'full' is the definition.
(synonyms)
'agreement we hear' is the wordplay.
'agreement' becomes 'pact' (pact is a kind of agreement).
'we hear' shows a homophone (sound like).
'pact' is a homophone of 'PACKED'.
(Other definitions for packed that I've seen before include "Enveloped" , "Placed clothes etc in suitcase" , "Arranged clothes in suitcase for travelling" , "Crowded" .)