Specimen politician put into auction (6)
I believe the answer is:
sample
'specimen' is the definition.
(I know that specimen can be written as sample)
'politician put into auction' is the wordplay.
'politician' becomes 'MP' (Member of Parliament).
'put into' means one lot of letters goes inside another.
'auction' becomes 'sale' (I've seen this in other clues).
'mp' put inside 'sale' is 'SAMPLE'.
(Other definitions for sample that I've seen before include "Drop of" , "Model" , "Taste; specimen" , "piece to try" , "Test the specimen" .)