Secure against shock though heartbroken (5)
I believe the answer is:
earth
'heartbroken' is the definition.
(heart anagrammed 'broken' can make earth)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for earth that I've seen before include "our present abode" , "Where some creatures live" , "Soil; ground terminal" , "See 12" , "Huge cost" .)