Cut wood goes to fires ultimately (5)
I believe the answer is:
steak
'cut' is the definition.
(cut of meat)
'wood goes to fires ultimately' is the wordplay.
'wood' becomes 'teak' (type of timber).
'goes to' means one lot of letters go next to another.
'ultimately' suggests the final letters.
The last letter of 'fires' is 's'.
'teak' put after 's' is 'STEAK'.
(Other definitions for steak that I've seen before include "Portion of meat" , "Cut of meat or fish" , "Porterhouse, perhaps?" , "High quality beef" , "- - tartare" .)