Prophet of a second coming before end of Christmas (4)
I believe the answer is:
amos
'prophet' is the definition.
(I've seen this before)
'a second coming before end of christmas' is the wordplay.
'second' becomes 'mo' (both are short periods of time).
'coming before' means one lot of letters go next to another.
'end of' says to take the final letters.
The last letter of 'christmas' is 's'.
'a'+'mo'+'s'='AMOS'
'of' is the link.
(Other definitions for amos that I've seen before include "Old Testament book" , "Old Testament prophet" , "Part of bible" , "Hebrew prophet" , "Biblical character" .)