Master cooking duck is genius (7)
I believe the answer is:
maestro
'genius' is the definition.
(I've seen this before)
'master cooking duck' is the wordplay.
'cooking' indicates anagramming the letters (cook can mean to falsify or distort).
'duck' becomes 'o' (resembles zero - 'duck' in cricket).
'master' anagrammed gives 'maestr'.
'maestr'+'o'='MAESTRO'
'is' acts as a link.
(Other definitions for maestro that I've seen before include "Expert in music etc" , "special performer" , "Virtuoso" , "An artist of consummate skill, master" , "musical genius" .)