Native American, according to Ivy (7)
I believe the answer is:
creeper
'ivy' is the definition.
(thesaurus)
'native american according' is the wordplay.
'native american' becomes 'cree' (an indigenous people of North America).
'according' becomes 'per' (I've seen this in other clues).
'cree'+'per'='CREEPER'
'to' acts as a link.
(Other definitions for creeper that I've seen before include "Ivy is one" , "Trailing plant" , "Climbing-plant" , "Say, Virginia" , "Reptile" .)