Raw material found in forests (3)
I believe the answer is:
ore
'raw material' is the definition.
'in forests' is the wordplay.
'in' says the answer is hidden in the clue.
'ORE' can be found hidden inside 'forests'.
'found' is the link.
(Other definitions for ore that I've seen before include "Raw mineral" , "not worth a lot to Danes" , "it could be gold" , "Raw iron" , "Mined material" .)