Country, one moving fast, by the sound of it? (6)
I believe the answer is:
russia
'country' is the definition.
(I know that Russia is a country)
'one moving fast by the sound of it?' is the wordplay.
'one moving fast' becomes 'rusher'.
'by the sound of it?' indicates a 'sounds like' (homophone) clue.
'rusher' sounds like 'RUSSIA'.
(Other definitions for russia that I've seen before include "Moscow's country" , "James Bond novel and film: 'From . . . . . . with Love'" , "World's largest country" , "Country where Omsk is situated" , "Eastern European state" .)