Raw materials from forest (4)
I believe the answer is:
ores
'raw materials' is the definition.
(I've seen this in another clue)
'from forest' is the wordplay.
'from' says the answer is hidden in the clue.
'ORES' can be found hidden inside 'forest'.
(Other definitions for ores that I've seen before include "Mineral deposits" , "Bauxite, haematite etc" , "Mined minerals" , "Rocks or minerals containing metals" , "Sources of metal" .)