Christmas fuel (4,3)
I believe the answer is:
yule log
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">christmas fuel</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for yule log that I've seen before include "Seasonal Christmas cake" , "It burns at Christmas" , "Chunk of wood for the Christmas fire" , "Large piece of firewood; cake" , "Something eaten (or burned?) at Christmas" .)