Pine exudation
I believe the answer is:
'pine exudation' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for resin that I've seen before include "varnish, perhaps" , "Sticky tree exudation" , "Contributor to plastics industry" , "Substance produced from sap of some plants and trees" , "Viscous substance in some trees" .)