Completely unfashionable element of the political spectrum? (8)
I believe the answer is:
outright
'completely' is the definition.
(thesaurus)
'unfashionable element of the political spectrum?' is the wordplay.
'unfashionable' becomes 'out' ('out' can be a synonym of 'unfashionable').
'element of the political spectrum?' becomes 'right'.
'out'+'right'='OUTRIGHT'
(Other definitions for outright that I've seen before include "Altogether; openly" , "straight away" , "Without reservation or exception" , "Complete; immediately" , "Openly and frankly" .)