Worked for nothing when confined (8)
I believe the answer is:
interned
'worked' is the definition.
(interning is a kind of working)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for interned that I've seen before include "deprived of freedom" , "With movement restricted" , "Locked up" , "Detained without trial" .)