Protect by taking out a policy (6)
I believe the answer is:
insure
'protect by taking out a policy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for insure that I've seen before include "Provide protection against risk or damage" , "Take out cover" , "Protect against possible loss" , "Arrange for payment in the event of loss" , "do business at Lloyds?" .)