South Africa’s hot belt (4)
I believe the answer is:
sash
'belt' is the definition.
(I've seen this before)
'south africa's hot' is the wordplay.
'south africa's' becomes 'sas' (abbreviation).
'hot' becomes 'h'.
'sas'+'h'='SASH'
(Other definitions for sash that I've seen before include "Girdle" , "Framework to hold the panes of a window" , "Band worn over shoulder or round waist" , "Style of window" , "(Uniform) strip; window-frame" .)