Unscramble what Enigma produced? (6)
I believe the answer is:
decode
'unscramble' is the definition.
(work out a code)
I can't explain the remainder of the clue.
(Other definitions for decode that I've seen before include "Convert a message into ordinary language" , "Break (a secret message)" , "Decipher, decrypt" , "Break a cipher" , "Crack (a secret message)" .)