Nutritious when well done (4,3,3)

I believe the answer is:

good for you

I'm a little stuck... Click here to teach me more about this clue!

'well done' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for good for you that I've seen before include "Well done! Health-giving" , "Vegetables are meant to be" , "Generally, fruit and veg is" , "congratulations" , "Very fatty steak may not be" .)

I've seen this clue in the Sydney Morning Herald.

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