Father supporting Southern resort (3)
I believe the answer is:
spa
'resort' is the definition.
(spa is a kind of resort)
'father supporting southern' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'southern' becomes 's' (abbreviation).
'pa' put after 's' is 'SPA'.
(Other definitions for spa that I've seen before include "here for healthy holiday" , "Water-cure town" , "Health and beauty treatment establishment" , "E.g. Harrogate" , "Boston" .)