He can sort the mail (4)
I believe the answer is:
liam
'he' is the definition.
'sort the mail' is the wordplay.
'sort' is an anagram indicator.
'mail' anagrammed gives 'LIAM'.
'can' is the link.
(Other definitions for liam that I've seen before include "-- Neeson (actor)" , "Irishman" , "Boy" .)