Such votes unusually hit new helpers welcoming Independent (5-4,5)

'such votes' is the definition.
(type of parliamentary vote)

'unusually hit new helpers welcoming independent' is the wordplay.
'unusually' indicates anagramming the letters.
'welcoming' indicates putting letters inside (in sense of 'inviting in').
'independent' becomes 'i'.
'hit'+'new'+'helpers'='hitnewhelpers'
'hitnewhelpers' with letters rearranged gives 'threelinewhps'.
'threelinewhps' placed around 'i' is 'THREE-LINE WHIPS'.