Resin for plastics (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
epoxy
(Other definitions for epoxy that I've seen before include "Synthetic adhesive, paint etc." , "Hard-setting resin" , "Synthetic resin used as glue" , "Synthetic polymer used in adhesives, paints, etc" , "Type of adhesive" .)