Surgical instrument produces utter chaos in church (7)
I believe the answer is:
curette
'surgical instrument' is the definition.
(curette is a kind of surgical instrument)
'utter chaos in church' is the wordplay.
'chaos' is an anagram indicator.
'in' means one lot of letters goes inside another.
'church' becomes 'ce' (abbreviation for Church of England).
'utter' is an anagram of 'urett'.
'urett' inserted inside 'ce' is 'CURETTE'.
'produces' acts as a link.
(Other definitions for curette that I've seen before include "Surgical scraper" , "Surgical instrument for removing dead tissue" .)