Thoroughly cooked (4)
I believe the answer is:
done
'thoroughly cooked' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for done that I've seen before include "Thoroughly cooked; accomplished" , "Finished like node" , "This sort of thing is socially acceptable" , "Tricked" , "Cooked; carried out" .)