Wintry weather in south, at present (4)
I believe the answer is:
snow
'wintry weather' is the definition.
(weather occurring in winter)
'south at present' is the wordplay.
'south' becomes 's' (abbreviation).
'at present' becomes 'now' (synonyms).
's'+'now'='SNOW'
'in' is the link.
(Other definitions for snow that I've seen before include "Cocaine (slang)" , "that may arrive around Christmas time" , "Settler" , "Basic White Christmas ingredient" , "Precipitation falling as flakes" .)