Individual gathering wood for burning (2,4)
I believe the answer is:
on fire
'burning' is the definition.
(thesaurus)
'individual gathering wood' is the wordplay.
'individual' becomes 'one'.
'gathering' is an insertion indicator.
'wood' becomes 'fir' (fir is a kind of wood).
'one' enclosing 'fir' is 'ON FIRE'.
'for' acts as a link.
(Other definitions for on fire that I've seen before include "in flames" , "Excited or ablaze" , "Enthusiastic" , "Eager" , "Alight" .)