Conservative facing constituent crony rejected nonsense (8)
I believe the answer is:
claptrap
'nonsense' is the definition.
(thesaurus)
'conservative facing constituent crony rejected' is the wordplay.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'facing' is a charade indicator (letters next to each other).
'constituent' becomes 'part' (I've seen this before**).
'crony' becomes 'pal' ('pal' can be a synonym of 'crony').
'rejected' shows that the letters should be reversed in order.
'part'+'pal'='partpal'
'partpal' reversed gives 'laptrap'.
'c'+'laptrap'='CLAPTRAP'
(Other definitions for claptrap that I've seen before include "Cobblers" , "Utter rubbish" , "Rhyme" , "Absurd or nonsensical talk or ideas" , "Bull" .)