Worker in South Africa sees Father Christmas (5)
I believe the answer is:
santa
'father christmas' is the definition.
(Santa Claus)
'worker in south africa' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'in' is an insertion indicator.
'south africa' becomes 'SA' (abbreviation).
'ant' placed inside 'sa' is 'SANTA'.
'sees' acts as a link.
(Other definitions for santa that I've seen before include "visitor bringing gifts" , "Present bringer" , "Dad in a red and white outfit?" , "The present chap" , "Midwinter gift bringer" .)