Midwesterner one performing around Washington (5)
I believe the answer is:
iowan
'midwesterner' is the definition.
(I've seen this before)
'one performing around washington' is the wordplay.
'one' becomes 'i' (Roman numeral).
'performing' becomes 'on' (as in being on stage).
'around' means one lot of letters goes inside another.
'washington' becomes 'wa' (abbreviation for the US state).
'on' enclosing 'wa' is 'owan'.
'i'+'owan'='IOWAN'
(Other definitions for iowan that I've seen before include "US resident" , "American" , "From a US state, capital Des Moines" , "From Des Moines, say?" , "Midwesterner" .)