Irishman throttling duke in chair (5)
I believe the answer is:
sedan
'chair' is the definition.
(sedan chair is a type of chair)
'irishman throttling duke' is the wordplay.
'irishman' becomes 'sean' (common Irish name).
'throttling' is an insertion indicator.
'duke' becomes 'd' (abbreviation).
'sean' going around 'd' is 'SEDAN'.
'in' is the link.
(Other definitions for sedan that I've seen before include "Type of chair - battle" , "Andes (anag.)" , "big chair" , "Chair to be carried by two" , "A closed litter for one passenger" .)