Former politician sitting in original early model (9)
I believe the answer is:
exemplary
'model' is the definition.
('exemplary' can be a synonym of 'model')
'former politician sitting in original early' is the wordplay.
'former' becomes 'ex'.
'politician' becomes 'mp'.
'sitting in' means one lot of letters goes inside another.
'original' is an anagram indicator.
'early' anagrammed gives 'elary'.
'mp' inserted inside 'elary' is 'emplary'.
'ex'+'emplary'='EXEMPLARY'
(Other definitions for exemplary that I've seen before include "Perfect" , "Outstandingly good, others should imitate" , "Ideal" , "Worthy of imitation" , "Worth following as an example" .)