A leader, inaccurate about western US state (8)
I believe the answer is:
delaware
'us state' is the definition.
(I've seen this before)
'a leader inaccurate about western' is the wordplay.
'inaccurate' indicates an anagram.
'about' means one lot of letters goes inside another.
'western' becomes 'w'.
'a'+'leader'='aleader'
'aleader' with letters rearranged gives 'delaare'.
'delaare' enclosing 'w' is 'DELAWARE'.
(Other definitions for delaware that I've seen before include "Second smallest US state" , "US state and river" , "State of eastern US" , "NE US state" , "state of the east" .)