Strong bond (5)
I believe the answer is:
epoxy
'strong bond' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for epoxy that I've seen before include "Synthetic resin used as glue" , "Type of adhesive" , "Type of adhesive/paint" , "Type of glue" , "Synthetic polymer used in adhesives, paints, etc" .)