Volunteer State
I think it could be either:
'volunteer state' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for tennessee that I've seen before include "Williams, say" , "Teen sense observed in American state" , "State of south-east US" , "Name of US dramatist" , "Volunteer State" .)
(Another definition for knoxville that I've seen is " US city".)