Head of state in Irish parliament to go off line (6)
I believe the answer is:
derail
'go off line' is the definition.
(I've seen this before)
'head of state in irish parliament' is the wordplay.
'head of state' becomes 'ER' (abbreviation for Elizabeth Regina).
'in' indicates putting letters inside.
'irish parliament' becomes 'dail' (I've seen this before).
'er' inserted into 'dail' is 'DERAIL'.
'to' is the link.
(Other definitions for derail that I've seen before include "go off line" , "go off track" , "Force off track, like a train" , "get off the line" , "Wilfully divert something from its intended course" .)