Fireplace essential part of first home (6)
I believe the answer is:
hearth
'fireplace' is the definition.
(synonyms)
'essential part of first home' is the wordplay.
'essential part' becomes 'heart' (I've seen this in another clue).
'of first' suggests taking the first letters (I've seen 'first' mean this).
The first letter of 'home' is 'h'.
'heart'+'h'='HEARTH'
(Other definitions for hearth that I've seen before include "fireside feature" , "Fireplace surround" , "Area around the fire" , "Novel" , "where the home is built?" .)