Politician introduced to corrupt earl by former model (8)
I believe the answer is:
exemplar
'model' is the definition.
(synonyms)
'politician introduced to corrupt earl by former' is the wordplay.
'politician' becomes 'mp' (Member of Parliament).
'introduced to' means one lot of letters goes inside another.
'corrupt' is an anagram indicator.
'by' is a charade indicator (letters next to each other).
'former' becomes 'ex'.
'earl' anagrammed gives 'elar'.
'mp' put within 'elar' is 'emplar'.
'emplar' put after 'ex' is 'EXEMPLAR'.
(Other definitions for exemplar that I've seen before include "Something serving as an appropriate model" , "Epitome" , "A good model or type" , "Typical specimen" , "Model to be followed" .)