No tension in parishioners clutching cross (6)
I believe the answer is:
laxity
'no tension' is the definition.
(laxity can mean an absence of tension)
'parishioners clutching cross' is the wordplay.
'parishioners' becomes 'laity' (I've seen this in another clue).
'clutching' indicates putting letters inside.
'cross' becomes 'x' (an X is a cross).
'laity' placed around 'x' is 'LAXITY'.
'in' is the link.
(Other definitions for laxity that I've seen before include "Looseness, slackness" , "Lack of precision" , "Neglect" , "Poor discipline, lack of authority" , "Carelessness or negligence" .)