Double corn mistakenly used in cookery (6,4)
I believe the answer is:
cordon bleu
'in cookery' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'double corn mistakenly' is the wordplay.
'mistakenly' indicates anagramming the letters.
'double'+'corn'='doublecorn'
'doublecorn' is an anagram of 'CORDON BLEU'.
'used' is the link.
Can you help me to learn more?
(Other definitions for cordon bleu that I've seen before include "Of a very high standard (food)" , "High-class cookery" , "distinguished chef" , "Highest class (cooking)" , "Old bouncer (anag)" .)