Where we all are, heading from fireplace (5)
I believe the answer is:
earth
'where we all are' is the definition.
(human home planet)
'heading from fireplace' is the wordplay.
'heading from' means to remove the first letter (remove the letter which heads the word).
'fireplace' becomes 'hearth' (synonyms).
'hearth' with its initial letter taken away is 'EARTH'.
(Other definitions for earth that I've seen before include "Human world" , "cost of which is very high" , "costs so much?" , "Connection between an electrical device and conductor" , "Solid ground" .)