Worry about nothing ancient predicted (8)
I believe the answer is:
foretold
'predicted' is the definition.
('foretold' can be a synonym of 'predicted')
'worry about nothing ancient' is the wordplay.
'worry' becomes 'fret' (fretting is a kind of worrying**).
'about' means one lot of letters goes inside another.
'nothing' becomes 'o' (looks like zero - 0).
'ancient' becomes 'old' ('old' can be similar in meaning to 'ancient').
'fret' placed around 'o' is 'foret'.
'foret'+'old'='FORETOLD'
(Another definition for foretold that I've seen is " Predicted".)