Functioning with company, leader of party once confronting us? (8)
I believe the answer is:
oncoming
'confronting us?' is the definition.
(if something is oncoming it's moving towards you)
'functioning with company leader of party once' is the wordplay.
'functioning' becomes 'on' (I've seen this in other clues).
'with' is a charade indicator (letters next to each other).
'company' becomes 'co' (abbreviation).
'leader of party once' becomes 'Ming' (Menzies 'Ming' Campbell, former Lib Dem leader).
'on'+'co'+'ming'='ONCOMING'
(Other definitions for oncoming that I've seen before include "1A [APPROACHING]" , "Moving towards one" .)