Stone from Northern Ireland featured in fireplace (7)
I believe the answer is:
granite
'stone' is the definition.
(granite is a kind of stone)
'northern ireland featured in fireplace' is the wordplay.
'northern ireland' becomes 'ni'.
'featured in' is an insertion indicator.
'fireplace' becomes 'grate' (I've seen this before).
'ni' placed inside 'grate' is 'GRANITE'.
'from' acts as a link.
(Other definitions for granite that I've seen before include "Showing great resolution" , "Crystalline rock" , "Hard stone from Tangier" , "Tangier (anag.)" , "A very hard rock from Tangier" .)