Dispatch to the southern extremity (4)
I believe the answer is:
send
'dispatch' is the definition.
(thesaurus)
'the southern extremity' is the wordplay.
'the southern' becomes 's' (abbreviation).
'extremity' becomes 'end' (end is a kind of extremity**).
's'+'end'='SEND'
'to' is the link.
(Other definitions for send that I've seen before include "Cause to go for" , "Transport" , "and 2: Advise" , "Forward" , "Consign" .)