Christmas visitors can include one conjuror (8)
I believe the answer is:
magician
'conjuror' is the definition.
(I know that conjuror can be written as magician)
'christmas visitors can include one' is the wordplay.
'christmas visitors' becomes 'magi' (the wise men of the nativity).
'include' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'can' going around 'i' is 'cian'.
'magi'+'cian'='MAGICIAN'
(Other definitions for magician that I've seen before include "Wizard like cartoon Mandrake" , "trickster" , "Sorcerer, wizard" , "Stage conjurer or maker of legerdemain" , "Conjuror, wizard" .)