Health resort in southern Pennsylvania (3)
I believe the answer is:
spa
'health resort' is the definition.
(thesaurus)
'southern pennsylvania' is the wordplay.
'southern' becomes 's' (abbreviation).
'pennsylvania' becomes 'pa'.
's'+'pa'='SPA'
'in' is the link.
(Other definitions for spa that I've seen before include "Resort with mineral water spring" , "hydro" , "Watering-place" , "Heated bath" , "where health benefits are offered" .)