Left impression, puncturing smart politician (8)
I believe the answer is:
blairite
'left impression puncturing smart politician' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'left impression puncturing smart politician' is the wordplay.
'left' becomes 'l' (common abbreviation).
'impression' becomes 'air' (I've seen this before).
'puncturing' means one lot of letters goes inside another (I've seen this in other clues).
'smart politician' becomes 'bite' (I can't justify this - if you can you should believe this answer much more).
'l'+'air'='lair'
'lair' going inside 'bite' is 'BLAIRITE'.
Can you help me to learn more?
(Other definitions for blairite that I've seen before include "Bluey-red" , "Of Labour's reforming policies" , "Tony's crony?" .)