Irene's wasted, having injected lousy chemical substance (5,5)
I believe the answer is:
epoxy resin
'chemical substance' is the definition.
'irene's wasted having injected lousy' is the wordplay.
'wasted' indicates an anagram.
'having injected' means one lot of letters goes inside another.
'lousy' becomes 'poxy'.
'irenes' with letters rearranged gives 'eresin'.
'eresin' placed around 'poxy' is 'EPOXY RESIN'.
(Other definitions for epoxy resin that I've seen before include "compound" , "This used to surface" , "Synthetic adhesive" , "synthetic material" .)