Firewood measures (5)
I believe the answer is:
cords
'firewood measures' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cords that I've seen before include "Flexes; trousers" , "sort of trousers" , "Electric flexes" , "Pieces of twine, say" , "Trousers of ribbed cloth" .)