Perfect if diet all evens out (5)
I believe the answer is:
ideal
'perfect' is the definition.
(similar in meaning)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for ideal that I've seen before include "Model of excellence (5)." , "faultless" , "Model of perfection" , "Model of ethical behaviour" , "Dream" .)