Christmas over: roast flipping pig (8)
I believe the answer is:
napoleon
'pig' is the definition.
(I've seen this before)
'christmas over roast flipping' is the wordplay.
'christmas' becomes 'Noel' (Noel can mean Christmas).
'over' becomes 'o' (cricket abbreviation).
'roast' becomes 'pan' (panning roast is a kind of roasting).
'flipping' says the letters should be written in reverse.
'noel'+'o'+'pan'='noelopan'
'noelopan' written backwards gives 'NAPOLEON'.
(Other definitions for napoleon that I've seen before include "Emperor - brandy" , "French general and emperor" , "Ruler" , "French emperor, d.1821" , "Cake" .)