Deck out, ornament (5)
I believe the answer is:
adorn
This clue is a double definition.
'deck out' is the first definition.
(I've seen this in another clue)
'ornament' is the second definition.
(synonyms)
(Other definitions for adorn that I've seen before include "Embellish, decorate" , "Festoon" , "Deck" , "Attire" , "Beautify - decorate - enhance" .)