Motel site is source of Yule deco (9)
I believe the answer is:
mistletoe
'yule deco' is the definition.
I can't tell whether this defines the answer.
'motel site is source of' is the wordplay.
'is source of' indicates anagramming the letters.
'motel'+'site'='motelsite'
'motelsite' anagrammed gives 'MISTLETOE'.
Can you help me to learn more?
(Other definitions for mistletoe that I've seen before include "put up for a Christmas function?" , "opportunity to kiss?" , "Valley of the -, best seller by Jacqueline Susann" , ""Kissing" sprig" , "White-berried parasite" .)