Stone jar seen round Northern Ireland (7)
I believe the answer is:
granite
'stone' is the definition.
(I've seen this before)
'jar seen round northern ireland' is the wordplay.
'jar' becomes 'grate' (make unpleasant sound).
'seen round' means one lot of letters goes inside another.
'northern ireland' becomes 'ni'.
'grate' enclosing 'ni' is 'GRANITE'.
(Other definitions for granite that I've seen before include "Coarse-grained igneous rock" , "Hard granular rock" , "A very hard rock from Tangier" , "Tearing (anag.)" , "Tangier (anag.)" .)