Copper featured in forgotten part of biblical plague (6)
I believe the answer is:
locust
'biblical plague' is the definition.
I know that 'plague' relates to this answer. I also know that both the answer and definition are singular nouns
'copper featured in forgotten' is the wordplay.
'copper' becomes 'Cu' (chemical symbol).
'featured in' is an insertion indicator.
'forgotten' becomes 'lost' (similar in meaning).
'cu' placed into 'lost' is 'LOCUST'.
'part of' acts as a link.
Can you help me to learn more?
(Other definitions for locust that I've seen before include "Ravenous insect" , "Destructive insect; tree" , "Clouts (anag)" , "Predatory grasshopper that swarms" , "Vegetation-destroying grasshopper" .)