Stop cooking with European sauce (5)
I believe the answer is:
pesto
'sauce' is the definition.
(pesto is a type of sauce)
'stop cooking with european' is the wordplay.
'cooking with' indicates anagramming the letters (cook can mean to falsify or distort).
'european' becomes 'E' (abbreviation e.g. EU).
'stop' mixed up with 'e' can make 'PESTO'.
(Other definitions for pesto that I've seen before include "A sauce served with pasta" , "Sauce made of basil and cheese" , "Italian sauce containing basil" , "Sauce of basil, pine nuts and garlic" , "Ligurian food" .)