Castro guessed insiders are nasty pieces of work (6)
I believe the answer is:
rogues
'pieces of work' is the definition.
Although both the answer and definition are plural nouns, I can't understand how one could define the other.
'castro guessed insiders are nasty' is the wordplay.
'ROGUES' is hidden in amongst the letters.
But, I'm unsure how this is indicated.
Can you help me to learn more?
(Other definitions for rogues that I've seen before include "Rascals" , "Scoundrels, miscreants" , "Varlets" , "Wild animals driven away from the herd" , "'Scoundrels, charlatans (6)'" .)