Right piece, wrong method (6)
I believe the answer is:
recipe
'method' is the definition.
(I've seen this before)
'right piece wrong' is the wordplay.
'right' becomes 'r' (common abbreviation).
'wrong' indicates an anagram.
'piece' anagrammed gives 'ecipe'.
'r'+'ecipe'='RECIPE'
(Other definitions for recipe that I've seen before include "Directions for food preparation" , "Cookery instructions" , "Instruction for cooking" , "Meal instructions" , "Directions for cooking a dish" .)