Criminal sinned when stealing church's cross (8)
I believe the answer is:
Here is my best explanation:
'cross' is the definition.
'criminal sinned when stealing church's' is the subsidiary indication.
I cannot really understand how this works, but
'church' could be 'ce' (abbreviation for Church of England) and 'ce' is present in the answer.
an anagram of 'sinned' is 'innsed' which is present in the remaining letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
(Other definitions for incensed that I've seen before include "Cross", "Very angry, really mad", "in a lather", "A high church may become so", "Enraged, furious", "Infuriated, outraged" and "Livid".)