Footwear is carbon free, for the record (3)
I believe the answer is:
log
'the record' is the definition.
(log is a kind of record)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for log that I've seen before include "Register" , "Ship's record" , "Record kept" , "number in mathematical table" , "Bulky piece of wood" .)