Moderates saints ring a lot... (7)
I believe the answer is:
softens
'moderates' is the definition.
('soften' can be a synonym of 'moderate')
'saints ring a lot' is the wordplay.
'saints' becomes 'ss' (an abbreviation for saint written twice).
'ring' is an insertion indicator.
'a lot' becomes 'often' (I've seen this before).
'ss' enclosing 'often' is 'SOFTENS'.
(Other definitions for softens that I've seen before include "Relaxes" , "Moderates" , "Makes less hard" , "begins to warm" .)