Diving equipment found in southern republic (5)
I believe the answer is:
scuba
'diving equipment' is the definition.
(I've seen this before)
'southern republic' is the wordplay.
'southern' becomes 's' (abbreviation).
'republic' becomes 'cuba' (Cuba is an example).
's'+'cuba'='SCUBA'
'found in' is the link.
(Other definitions for scuba that I've seen before include "Skin-diver's device" , "Sort of diver" , "breather" , "Device that lets divers breathe under water" , "Diving apparatus" .)