Quiet is helping gripping account (7)
I believe the answer is:
placate
'quiet' is the definition.
Although both the answer and definition are verbs in their base form, I don't see how one could define the other.
'helping gripping account' is the wordplay.
'helping' becomes 'plate'.
'gripping' is an insertion indicator (inserted letters are gripped).
'account' becomes 'ca' (I've seen this in other clues).
'plate' enclosing 'ca' is 'PLACATE'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for placate that I've seen before include "Make less angry" , "Mollify, appease" , "Mollify, calm down" , "Mollify, soothe anger" , "'Pacify, appease (7)'" .)