Manifestation of good in evil? (4)
I believe the answer is:
sign
'manifestation' is the definition.
(thesaurus)
'good in evil?' is the wordplay.
'good' becomes 'g' (abbreviation).
'in' is an insertion indicator.
'evil?' becomes 'sin' (I've seen this before).
'g' inserted inside 'sin' is 'SIGN'.
'of' acts as a link.
(Other definitions for sign that I've seen before include "Show" , "Engage by written agreement" , "Mark" , "Public notice; portent" , "Any of the 12 divisions of the Zodiac" .)