December talk: what we could hang on the tree (10)
I believe the answer is:
decoration
'what we could hang on the tree' is the definition.
(as in a Christmas tree decoration)
'december talk' is the wordplay.
'december' becomes 'Dec' (synonyms).
'talk' becomes 'oration'.
'dec'+'oration'='DECORATION'
(Other definitions for decoration that I've seen before include "New Year's honour, say" , "Star" , "Adornment - medal" , "Ornaments - medal" , "Bunting (in honour of a brave man?)" .)