Light French cheese sounded rubbish (6)
I believe the answer is:
debris
'rubbish' is the definition.
(debris is a kind of rubbish)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for debris that I've seen before include "Scattered wreckage" , "Brides with pieces of rubble" , "Remains - wreckage" , "Scattered rubbish" , "Broken remains" .)