Disparaging term for a medium asteroid orbiting round America (5,5)
I believe the answer is:
steam radio
'disparaging term for a medium' is the definition.
(mocking term for radio compared with newer media)
'asteroid orbiting round america' is the wordplay.
'orbiting' indicates anagramming the letters (letters move or orbit to new positions).
'round' means one lot of letters goes inside another.
'america' becomes 'am'.
'asteroid' is an anagram of 'steradio'.
'steradio' going around 'am' is 'STEAM RADIO'.
(Other definitions for steam radio that I've seen before include "style of broadcasting" , "wireless" , "form of broadcasting?" .)