Christmas visitors can include one conjurer (8)
I believe the answer is:
magician
'conjurer' is the definition.
('magician' can be a synonym of 'conjurer')
'christmas visitors can include one' is the wordplay.
'christmas visitors' becomes 'magi' (I've seen this in other clues).
'include' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'can' going around 'i' is 'cian'.
'magi'+'cian'='MAGICIAN'
(Other definitions for magician that I've seen before include "Sorcerer, wizard" , "Conjurer, illusionist" , "Conjuror, wizard" , "A stage illusionist, or cartoon Mandrake" , "Prestidigitator" .)