A world of new heart (5)

I believe the answer is:

earth

'a world' is the definition.
('Earth' can be a synonym of 'world')

'new heart' is the wordplay.
'new' is an anagram indicator.
'heart' is an anagram of 'EARTH'.

'of' is the link.

(Other definitions for earth that I've seen before include "electrical safety precaution" , "Heart (anag)" , "World - soil" , "Soil; fox's lair" , "Land" .)

I've seen this clue in the Evening Standard.

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