Summary is not entirely accurate (6)
I believe the answer is:
precis
'summary' is the definition.
(precis is a kind of summary)
'not entirely accurate' is the wordplay.
'not entirely' means to remove the last letter (not all of the word).
'accurate' becomes 'precise' (synonyms).
'precise' with its last letter taken away is 'PRECIS'.
'is' is the link.
(Other definitions for precis that I've seen before include "Summary, short version" , "Digest - summary" , "Abridgment (of text)" , "Cripes, what a summary!" , "Summary of the main points" .)