It's obtained from tree-sap (5)
I believe the answer is:
resin
'it's obtained from tree-sap' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for resin that I've seen before include "Sticky exudation from trees" , "viscous material" , "Contributor to plastics industry" , "Exudation from fir trees" , "hashish, say" .)