Can it split? Confess (6)
'confess' is the definition.
'can it split?' is the wordplay.
'can it' becomes 'sh' ('can it' can mean stop talking or be quiet).
'split?' becomes 'rive' ('rive' can be a synonym of 'split').
(Other definitions for shrive that I've seen before include "Confess", "Shiver in giving absolution in confession", "Old word meaning to hear confession and give absolution".)