A feast assists one worked up about nothing (6)

I believe the answer is:

isodia

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

'a feast' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Another definition for isodia that I've seen is " A feast".)

I've seen this clue in The Times and The Sunday Times.

Want a hint initially instead of a full solution? Install my app