Maybe one left at Xmas (4)
I believe the answer is:
noel
'xmas' is the definition.
(I've seen this before)
'maybe one left' is the wordplay.
'maybe' indicates anagramming the letters.
'left' becomes 'l' (common abbreviation).
'one' is an anagram of 'noe'.
'noe'+'l'='NOEL'
'at' is the link.
(Other definitions for noel that I've seen before include "A lone sort of Christmas" , "- - Coward, playwright" , "A lone French Christmas" , "Season around the 25th December" , "Religious festival" .)