Moral values in middle of fifteenth century recorded in this (6)
I believe the answer is:
ethics
'moral values' is the definition.
(I've seen this before)
'middle of fifteenth century recorded in this' is the wordplay.
'middle of' means to look at the middle letters.
'century' becomes 'c' (common abbreviation).
'recorded in' indicates putting letters inside.
The middle letter of 'fifteenth' is 'e'.
'c' going inside 'this' is 'thics'.
'e'+'thics'='ETHICS'
'in' is the link.
(Other definitions for ethics that I've seen before include "Codes of conduct in business affairs" , "Some philosophy" , "System of morals" , "Principles to be observed by business and professions" , "Moral principles in middle" .)