All letters redirected, watch post (5)
I believe the answer is:
remit
'post' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for remit that I've seen before include "Transfer - area of authority" , "The - Papers (M. Amis)" , "Orders" , "Maybe suspend" , "committee's brief" .)