Insufficient cause to include a politician on educational grounds (6)
I believe the answer is:
campus
'educational grounds' is the definition.
(I've seen this before)
'insufficient cause to include a politician' is the wordplay.
'insufficient' means to remove the last letter.
'to include' is an insertion indicator.
'a politician' becomes 'MP' (Member of Parliament).
'cause' with its final letter removed is 'caus'.
'caus' going around 'mp' is 'CAMPUS'.
'on' is the link.
(Other definitions for campus that I've seen before include "University grounds, etc" , "buildings in Nottingham, say" , "Grounds of university or college" , "university territory" , "University location" .)