Multum in parvo is less than accurate (6)
I believe the answer is:
precis
'multum in parvo' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see an association between them that I can't see?
'less than accurate' is the wordplay.
'less than' means to remove the last letter (not the full word).
'accurate' becomes 'precise' (synonyms).
'precise' with its last letter removed is 'PRECIS'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for precis that I've seen before include "Summary of the main points" , "Summarize" , "Summary, short version" , "Prices for a summary" , "Abstract; make summary (of text)" .)