Joint vote cast in Irish parliament (8)
I believe the answer is:
dovetail
'joint' is the definition.
(I've seen this before)
'vote cast in irish parliament' is the wordplay.
'cast' indicates anagramming the letters.
'in' means one lot of letters goes inside another.
'irish parliament' becomes 'dail' (I've seen this before).
'vote' anagrammed gives 'ovet'.
'ovet' inserted into 'dail' is 'DOVETAIL'.
(Other definitions for dovetail that I've seen before include "Ali voted (anag) - joint" , "Joint of tenon and mortise" , "Wood joint" , "good joint" , "Interlocking joint" .)