The most common and most likely answer to this crossword clue is the 8 letter word SPOILAGE
I've seen this crossword clue in The Daily Telegraph
S
P
O
I
L
A
G
E
Buddy explains!

The straight part
We know that "Wasted material" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wasted material = spoilage.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SPOILAGE mean?
SPOILAGE noun- The part of something that has spoiled.
- The process of spoiling.