This heart-breaking world (5)

I believe the answer is:

earth

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

'world' is the definition.
(synonyms)

'this heart-breaking' is the wordplay.
'heart' anagrams to 'EARTH'.
But, I am not clear how the anagram is indicated.

Can you help me to learn more?

(Other definitions for earth that I've seen before include "electrical safety precaution" , "Where some creatures live" , "Soil; electrical ground" , "Connection between an electrical device and conductor" , "Third planet from the Sun" .)

I've seen this clue in the Evening Standard.

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