Heard man get some letters (4)
I believe the answer is:
'some letters' is the definition.
(letters sent in the post or mail)
'heard man' is the wordplay.
'heard' shows a homophone (sound like).
'man' becomes 'male'.
'male' is a homophone of 'MAIL'.
'get' acts as a link.
(Other definitions for mail that I've seen before include "Posted letters" , "American post from Lima" , "Flexible armour" , "some self-defence material" , "Eg, letters" .)