Unappreciative person at home, next to fireplace (7)
I believe the answer is:
ingrate
'unappreciative person' is the definition.
(I've seen this before)
'home next to fireplace' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'next to' means one lot of letters go next to another.
'fireplace' becomes 'grate' (grate can mean a fireplace).
'in'+'grate'='INGRATE'
'at' is the link.
(Other definitions for ingrate that I've seen before include "Thankless wretch" , "Thankless sort" , "No thanks, I say!" , "without a word of thanks?" , "One who never says thanks" .)