Conservative to drink gin that's rubbish (8)
I believe the answer is:
claptrap
'rubbish' is the definition.
(I've seen this before)
'conservative to drink gin' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'to drink' becomes 'lap' (lap can mean to drink).
'gin' becomes 'trap' (I've seen this in other clues).
'c'+'lap'+'trap'='CLAPTRAP'
'that's' is the link.
(Other definitions for claptrap that I've seen before include "Meaningless, insincere or pompous talk" , "Meaningless nonsense" , "Tripe" , "Absurd or nonsensical talk or ideas" , "Pretentious rot" .)