Painter found in area south of Rio Grande, say (6)
I believe the answer is:
rivera
'painter' is the definition.
(thesaurus)
'area south of rio grande say' is the wordplay.
'area' becomes 'a' (maths abbreviation).
'south of' is a charade indicator (letters next to each other).
'rio grande say' becomes 'river' (rio grande is a kind of river).
'a' put after 'river' is 'RIVERA'.
'found in' acts as a link.
(Other definitions for rivera that I've seen before include "Painter" , "Revolutionary artist" .)