Areas where saints are out of step (6)
I believe the answer is:
spaces
'areas' is the definition.
(I know this)
'saints are out of step' is the wordplay.
'saints' becomes 'ss'.
'are out of' is an insertion indicator (some letters on the outside of others).
'step' becomes 'pace' (pace is a kind of step).
'ss' placed around 'pace' is 'SPACES'.
'where' acts as a link.
(Other definitions for spaces that I've seen before include "Open areas" , "Gaps" , "distances" , "Blank areas" , "cleared areas" .)