Irishman visiting close relative, heretical legislator (15)
I believe the answer is:
parliamentarian
'legislator' is the definition.
(I've seen this before)
'irishman visiting close relative heretical' is the wordplay.
'irishman' becomes 'liam' (common Irish name).
'visiting' indicates putting letters inside.
'close relative' becomes 'parent' (one's parents are close relatives).
'heretical' becomes 'arian' (I've seen this in other clues).
'liam' inserted inside 'parent' is 'parliament'.
'parliament'+'arian'='PARLIAMENTARIAN'
(Other definitions for parliamentarian that I've seen before include "politician" , "elected representative?" , "Eg, an MP" , "legislator" .)