The world is heartbroken (5)
I believe the answer is:
earth
This clue is a double definition.
'the world' is the first definition.
('Earth' can be a synonym of 'world')
'heartbroken' is the second definition.
(heart anagrammed 'broken' can make earth)
'is' is the link.
(Other definitions for earth that I've seen before include "Where some creatures live" , "Our favourite planet" , "our home" , "Heart of clay" , "hideaway" .)