Reject Christmas work with an emperor (8)
I believe the answer is:
napoleon
'emperor' is the definition.
(I know that Napoleon is a emperor)
'reject christmas work with an' is the wordplay.
'reject' is a reversal indicator.
'christmas' becomes 'Noel' (Noel can mean Christmas).
'work' becomes 'op' (common abbreviation for 'opus').
'with' is a charade indicator (letters next to each other).
'noel'+'op'+'an'='noelopan'
'noelopan' reversed gives 'NAPOLEON'.
(Other definitions for napoleon that I've seen before include "French general and emperor" , "In France, former sovereign" , "French emperor, d.1821" , "Former French gold coin" , "Old French coin" .)