Adorn, festoon (6)
I believe the answer is:
bedeck
This clue is a double definition.
'adorn' is the first definition.
(bedecking is a kind of adorning)
'festoon' is the second definition.
(I've seen this in another clue)
(Other definitions for bedeck that I've seen before include "Adorn, embellish" , "Trim" , "Festoon; decorate" , "Embellish with adornments" , "Festoon, adorn" .)