Agree cooking is keen (5)
I believe the answer is:
eager
'keen' is the definition.
(I've seen this before)
'agree cooking' is the wordplay.
'cooking' indicates anagramming the letters (cook can mean to falsify or distort).
'agree' is an anagram of 'EAGER'.
'is' acts as a link.
(Other definitions for eager that I've seen before include "Whole-hearted" , "hungry" , "Keen (as a beaver?)" , "Alert and active type?" , "Excited by desire" .)