Pole teacher who handles letters (10)
I believe the answer is:
'pole teacher who handles letters' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'pole teacher' is the wordplay.
'pole' becomes 'post' (I've seen this before).
'teacher' becomes 'master' (I've seen this before).
Can you help me to learn more?
(Other definitions for postmaster that I've seen before include "who runs a local office?", "Mail chief".)