Conservative getting rougher and rougher (6)
I believe the answer is:
cruder
'rougher' is the definition.
('crude' can be similar in meaning to 'rough')
'conservative getting rougher' is the wordplay.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'getting' is a charade indicator (letters next to each other).
'rougher' becomes 'ruder' ('rude' can be similar in meaning to 'rough').
'c'+'ruder'='CRUDER'
'and' is the link.
(Other definitions for cruder that I've seen before include "Less refined, more vulgar" , "Less refined, more primitive" .)