Moan and lie about after last of Xmas pudding (8)
I believe the answer is:
semolina
'pudding' is the definition.
(I've seen this before)
'moan and lie about after last of xmas' is the wordplay.
'and' means one lot of letters go next to another (I've seen this in other clues).
'about' indicates anagramming the letters.
'after' is a charade indicator (letters next to each other).
'last of' says to take the final letters.
The last letter of 'xmas' is 's'.
'moan' put after 'lie' is 'liemoan'.
'liemoan' anagrammed gives 'emolina'.
'emolina' after 's' is 'SEMOLINA'.
(Other definitions for semolina that I've seen before include "Is no meal (anag.)" , "Type of milk pudding" , "Wheat powder" , "Wheat product used in pasta" , "Lemon is a strange pasta" .)