Heard man get letters (4)
I believe the answer is:
'letters' is the definition.
(letters sent in the post or mail)
'heard man' is the wordplay.
'heard' indicates a 'sounds like' (homophone) clue.
'man' becomes 'male'.
'male' is a homophone of 'MAIL'.
'get' is the link.
(Other definitions for mail that I've seen before include "letter?" , "Form of armour; post" , "protective cover" , "Flexible armour" , "some self-defence material" .)