Guard southern way in (6)
I believe the answer is:
sentry
'guard' is the definition.
(sentry is a kind of guard)
'southern way in' is the wordplay.
'southern' becomes 's' (abbreviation).
'way in' becomes 'entry' (I've seen this before).
's'+'entry'='SENTRY'
(Other definitions for sentry that I've seen before include "One keeps guard" , "Look-out, guard" , "Mil. guard" , "One posted on guard" , "Watchperson" .)