Purification of medieval Christians' lives (9)
I believe the answer is:
catharsis
'purification' is the definition.
(I've seen this before)
'medieval christians' lives' is the wordplay.
'medieval christians'' becomes 'cathars' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'lives' becomes 'is' ('be' can be a synonym of 'live').
'cathars'+'is'='CATHARSIS'
'of' is the link.
Can you help me to learn more?
(Other definitions for catharsis that I've seen before include "Purification of the emotions" , "Purification - is rash act (anag)" , "The release of pent-up emotions" , "emotional relief" , "Emotional release" .)