Embellishment of Christmas speech? (10)
I believe the answer is:
decoration
'embellishment' is the definition.
(thesaurus)
'christmas speech?' is the wordplay.
'christmas' becomes 'dec' (Dec is short for December, the Christmas period).
'speech?' becomes 'oration' (oration is a kind of speech).
'dec'+'oration'='DECORATION'
'of' is the link.
(Other definitions for decoration that I've seen before include "Adornment - medal" , "Flags put out" , "Bunting (in honour of a brave man?)" , "New Year's honour, say" , "Medal; ornament" .)