Maine's not bad for a US state (9)
I believe the answer is:
minnesota
'a us state' is the definition.
(I've seen this before)
'maine's not bad' is the wordplay.
'bad' indicates an anagram.
'maines'+'not'='mainesnot'
'mainesnot' is an anagram of 'MINNESOTA'.
'for' is the link.
(Other definitions for minnesota that I've seen before include "US state, capital St Paul" , "Wobegon state (Keillor)" , "Nominates the strange state" , "Nominates, oddly, the US state" , "North Star State" .)