Bliss of Northern Ireland artist securing leading position (7)
I believe the answer is:
nirvana
'bliss' is the definition.
(blissful state in Buddhism)
'northern ireland artist securing leading position' is the wordplay.
'northern ireland' becomes 'NI' (abbreviation).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'securing' means one lot of letters goes inside another.
'leading position' becomes 'van' (term for the front of a group eg a military group).
'ra' going around 'van' is 'rvana'.
'ni'+'rvana'='NIRVANA'
'of' acts as a link.
(Other definitions for nirvana that I've seen before include "Eastern place of complete bliss" , "Buddhists' transcendental state" , "Buddhist state of bliss; enlightenment" , "Transcendent state of Buddhists" , "Tranquillity" .)