Standards identified by exam in writing (6)
I believe the answer is:
morals
'standards' is the definition.
(I have seen 'Standards of behaviour ' mean 'morals' so perhaps 'standards' could also mean 'morals')
'exam in writing' is the wordplay.
'exam' becomes 'oral' (spoken academic test).
'in' means one lot of letters goes inside another.
'writing' becomes 'ms' (abbreviation for manuscript).
'oral' put into 'ms' is 'MORALS'.
'identified by' acts as a link.
(Other definitions for morals that I've seen before include "High principles or ethics" , "Standards of behaviour" , "Ethical motives" , "Principles based on right and wrong" , "code?" .)